aboutsummaryrefslogtreecommitdiffstats
path: root/testhal/STM32/STM32L1xx/ADC/chconf.h
blob: 566d7ecf3c5e3cdbf56dfd2d27e28aa2566380b6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
/*
    ChibiOS - Copyright (C) 2006..2016 Giovanni Di Sirio

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/

/**
 * @file    templates/chconf.h
 * @brief   Configuration file template.
 * @details A copy of this file must be placed in each project directory, it
 *          contains the application specific kernel settings.
 *
 * @addtogroup config
 * @details Kernel related settings and hooks.
 * @{
 */

#ifndef CHCONF_H
#define CHCONF_H

#define _CHIBIOS_RT_CONF_
#define _CHIBIOS_RT_CONF_VER_5_0_

/*===========================================================================*/
/**
 * @name System timers settings
 * @{
 */
/*===========================================================================*/

/**
 * @brief   System time counter resolution.
 * @note    Allowed values are 16 or 32 bits.
 */
#define CH_CFG_ST_RESOLUTION                16

/**
 * @brief   System tick frequency.
 * @details Frequency of the system timer that drives the system ticks. This
 *          setting also defines the system tick time unit.
 */
#define CH_CFG_ST_FREQUENCY                 1000

/**
 * @brief   Time delta constant for the tick-less mode.
 * @note    If this value is zero then the system uses the classic
 *          periodic tick. This value represents the minimum number
 *          of ticks that is safe to specify in a timeout directive.
 *          The value one is not valid, timeouts are rounded up to
 *          this value.
 */
#define CH_CFG_ST_TIMEDELTA                 2

/** @} */

/*===========================================================================*/
/**
 * @name Kernel parameters and options
 * @{
 */
/*===========================================================================*/

/**
 * @brief   Round robin interval.
 * @details This constant is the number of system ticks allowed for the
 *          threads before preemption occurs. Setting this value to zero
 *          disables the preemption for threads with equal priority and the
 *          round robin becomes cooperative. Note that higher priority
 *          threads can still preempt, the kernel is always preemptive.
 * @note    Disabling the round robin preemption makes the kernel more compact
 *          and generally faster.
 * @note    The round robin preemption is not supported in tickless mode and
 *          must be set to zero in that case.
 */
#define CH_CFG_TIME_QUANTUM                 0

/**
 * @brief   Managed RAM size.
 * @details Size of the RAM area to be managed by the OS. If set to zero
 *          then the whole available RAM is used. The core memory is made
 *          available to the heap allocator and/or can be used directly through
 *          the simplified core memory allocator.
 *
 * @note    In order to let the OS manage the whole RAM the linker script must
 *          provide the @p __heap_base__ and @p __heap_end__ symbols.
 * @note    Requires @p CH_CFG_USE_MEMCORE.
 */
#define CH_CFG_MEMCORE_SIZE                 0

/**
 * @brief   Idle thread automatic spawn suppression.
 * @details When this option is activated the function @p chSysInit()
 *          does not spawn the idle thread. The application @p main()
 *          function becomes the idle thread and must implement an
 *          infinite loop.
 */
#define CH_CFG_NO_IDLE_THREAD               FALSE

/** @} */

/*===========================================================================*/
/**
 * @name Performance options
 * @{
 */
/*===========================================================================*/

/**
 * @brief   OS optimization.
 * @details If enabled then time efficient rather than space efficient code
 *          is used when two possible implementations exist.
 *
 * @note    This is not related to the compiler optimization options.
 * @note    The default is @p TRUE.
 */
#define CH_CFG_OPTIMIZE_SPEED               TRUE

/** @} */

/*===========================================================================*/
/**
 * @name Subsystem options
 * @{
 */
/*===========================================================================*/

/**
 * @brief   Time Measurement APIs.
 * @details If enabled then the time measurement APIs are included in
 *          the kernel.
 *
 * @note    The default is @p TRUE.
 */
#define CH_CFG_USE_TM                       TRUE

/**
 * @brief   Threads registry APIs.
 * @details If enabled then the registry APIs are included in the kernel.
 *
 * @note    The default is @p TRUE.
 */
#define CH_CFG_USE_REGISTRY                 TRUE

/**
 * @brief   Threads synchronization APIs.
 * @details If enabled then the @p chThdWait() function is included in
 *          the kernel.
 *
 * @note    The default is @p TRUE.
 */
#define CH_CFG_USE_WAITEXIT                 TRUE

/**
 * @brief   Semaphores APIs.
 * @details If enabled then the Semaphores APIs are included in the kernel.
 *
 * @note    The default is @p TRUE.
 */
#define CH_CFG_USE_SEMAPHORES               TRUE

/**
 * @brief   Semaphores queuing mode.
 * @details If enabled then the threads are enqueued on semaphores by
 *          priority rather than in FIFO order.
 *
 * @note    The default is @p FALSE. Enable this if you have special
 *          requirements.
 * @note    Requires @p CH_CFG_USE_SEMAPHORES.
 */
#define CH_CFG_USE_SEMAPHORES_PRIORITY      FALSE

/**
 * @brief   Mutexes APIs.
 * @details If enabled then the mutexes APIs are included in the kernel.
 *
 * @note    The default is @p TRUE.
 */
#define CH_CFG_USE_MUTEXES                  TRUE

/**
 * @brief   Enables recursive behavior on mutexes.
 * @note    Recursive mutexes are heavier and have an increased
 *          memory footprint.
 *
 * @note    The default is @p FALSE.
 * @note    Requires @p CH_CFG_USE_MUTEXES.
 */
#define CH_CFG_USE_MUTEXES_RECURSIVE        FALSE

/**
 * @brief   Conditional Variables APIs.
 * @details If enabled then the conditional variables APIs are included
 *          in the kernel.
 *
 * @note    The default is @p TRUE.
 * @note    Requires @p CH_CFG_USE_MUTEXES.
 */
#define CH_CFG_USE_CONDVARS                 TRUE

/**
 * @brief   Conditional Variables APIs with timeout.
 * @details If enabled then the conditional variables APIs with timeout
 *          specification are included in the kernel.
 *
 * @note    The default is @p TRUE.
 * @note    Requires @p CH_CFG_USE_CONDVARS.
 */
#define CH_CFG_USE_CONDVARS_TIMEOUT         TRUE

/**
 * @brief   Events Flags APIs.
 * @details If enabled then the event flags APIs are included in the kernel.
 *
 * @note    The default is @p TRUE.
 */
#define CH_CFG_USE_EVENTS                   TRUE

/**
 * @brief   Events Flags APIs with timeout.
 * @details If enabled then the events APIs with timeout specification
 *          are included in the kernel.
 *
 * @note    The default is @p TRUE.
 * @note    Requires @p CH_CFG_USE_EVENTS.
 */
#define CH_CFG_USE_EVENTS_TIMEOUT           TRUE

/**
 * @brief   Synchronous Messages APIs.
 * @details If enabled then the synchronous messages APIs are included
 *          in the kernel.
 *
 * @note    The default is @p TRUE.
 */
#define CH_CFG_USE_MESSAGES                 TRUE

/**
 * @brief   Synchronous Messages queuing mode.
 * @details If enabled then messages are served by priority rather than in
 *          FIFO order.
 *
 * @note    The default is @p FALSE. Enable this if you have special
 *          requirements.
 * @note    Requires @p CH_CFG_USE_MESSAGES.
 */
#define CH_CFG_USE_MESSAGES_PRIORITY        FALSE

/**
 * @brief   Mailboxes APIs.
 * @details If enabled then the asynchronous messages (mailboxes) APIs are
 *          included in the kernel.
 *
 * @note    The default is @p TRUE.
 * @note    Requires @p CH_CFG_USE_SEMAPHORES.
 */
#define CH_CFG_USE_MAILBOXES                TRUE

/**
 * @brief   Core Memory Manager APIs.
 * @details If enabled then the core memory manager APIs are included
 *          in the kernel.
 *
 * @note    The default is @p TRUE.
 */
#define CH_CFG_USE_MEMCORE                  TRUE

/**
 * @brief   Heap Allocator APIs.
 * @details If enabled then the memory heap allocator APIs are included
 *          in the kernel.
 *
 * @note    The default is @p TRUE.
 * @note    Requires @p CH_CFG_USE_MEMCORE and either @p CH_CFG_USE_MUTEXES or
 *          @p CH_CFG_USE_SEMAPHORES.
 * @note    Mutexes are recommended.
 */
#define CH_CFG_USE_HEAP                     TRUE

/**
 * @brief   Memory Pools Allocator APIs.
 * @details If enabled then the memory pools allocator APIs are included
 *          in the kernel.
 *
 * @note    The default is @p TRUE.
 */
#define CH_CFG_USE_MEMPOOLS                 TRUE

/**
 * @brief  Objects FIFOs APIs.
 * @details If enabled then the objects FIFOs APIs are included
 *          in the kernel.
 *
 * @note    The default is @p TRUE.
 */
#define CH_CFG_USE_OBJ_FIFOS                TRUE

/**
 * @brief   Dynamic Threads APIs.
 * @details If enabled then the dynamic threads creation APIs are included
 *          in the kernel.
 *
 * @note    The default is @p TRUE.
 * @note    Requires @p CH_CFG_USE_WAITEXIT.
 * @note    Requires @p CH_CFG_USE_HEAP and/or @p CH_CFG_USE_MEMPOOLS.
 */
#define CH_CFG_USE_DYNAMIC                  TRUE

/** @} */

/*===========================================================================*/
/**
 * @name Objects factory options
 * @{
 */
/*===========================================================================*/

/**
 * @brief   Objects Factory APIs.
 * @details If enabled then the objects factory APIs are included in the
 *          kernel.
 *
 * @note    The default is @p FALSE.
 */
#define CH_CFG_USE_FACTORY                  TRUE

/**
 * @brief   Maximum length for object names.
 * @details If the specified length is zero then the name is stored by
 *          pointer but this could have unintended side effects.
 */
#define CH_CFG_FACTORY_MAX_NAMES_LENGTH     8

/**
 * @brief   Enables the registry of generic objects.
 */
#define CH_CFG_FACTORY_OBJECTS_REGISTRY     TRUE

/**
 * @brief   Enables factory for generic buffers.
 */
#define CH_CFG_FACTORY_GENERIC_BUFFERS      TRUE

/**
 * @brief   Enables factory for semaphores.
 */
#define CH_CFG_FACTORY_SEMAPHORES           TRUE

/**
 * @brief   Enables factory for mailboxes.
 */
#define CH_CFG_FACTORY_MAILBOXES            TRUE

/**
 * @brief   Enables factory for objects FIFOs.
 */
#define CH_CFG_FACTORY_OBJ_FIFOS            TRUE

/** @} */

/*===========================================================================*/
/**
 * @name Debug options
 * @{
 */
/*===========================================================================*/

/**
 * @brief   Debug option, kernel statistics.
 *
 * @note    The default is @p FALSE.
 */
#define CH_DBG_STATISTICS                   FALSE

/**
 * @brief   Debug option, system state check.
 * @details If enabled the correct call protocol for system APIs is checked
 *          at runtime.
 *
 * @note    The default is @p FALSE.
 */
#define CH_DBG_SYSTEM_STATE_CHECK           TRUE

/**
 * @brief   Debug option, parameters checks.
 * @details If enabled then the checks on the API functions input
 *          parameters are activated.
 *
 * @note    The default is @p FALSE.
 */
#define CH_DBG_ENABLE_CHECKS                TRUE

/**
 * @brief   Debug option, consistency checks.
 * @details If enabled then all the assertions in the kernel code are
 *          activated. This includes consistency checks inside the kernel,
 *          runtime anomalies and port-defined checks.
 *
 * @note    The default is @p FALSE.
 */
#define CH_DBG_ENABLE_ASSERTS               TRUE

/**
 * @brief   Debug option, trace buffer.
 * @details If enabled then the trace buffer is activated.
 *
 * @note    The default is @p CH_DBG_TRACE_MASK_DISABLED.
 */
#define CH_DBG_TRACE_MASK                   CH_DBG_TRACE_MASK_ALL

/**
 * @brief   Trace buffer entries.
 * @note    The trace buffer is only allocated if @p CH_DBG_TRACE_MASK is
 *          different from @p CH_DBG_TRACE_MASK_DISABLED.
 */
#define CH_DBG_TRACE_BUFFER_SIZE            128

/**
 * @brief   Debug option, stack checks.
 * @details If enabled then a runtime stack check is performed.
 *
 * @note    The default is @p FALSE.
 * @note    The stack check is performed in a architecture/port dependent way.
 *          It may not be implemented or some ports.
 * @note    The default failure mode is to halt the system with the global
 *          @p panic_msg variable set to @p NULL.
 */
#define CH_DBG_ENABLE_STACK_CHECK           TRUE

/**
 * @brief   Debug option, stacks initialization.
 * @details If enabled then the threads working area is filled with a byte
 *          value when a thread is created. This can be useful for the
 *          runtime measurement of the used stack.
 *
 * @note    The default is @p FALSE.
 */
#define CH_DBG_FILL_THREADS                 TRUE

/**
 * @brief   Debug option, threads profiling.
 * @details If enabled then a field is added to the @p thread_t structure that
 *          counts the system ticks occurred while executing the thread.
 *
 * @note    The default is @p FALSE.
 * @note    This debug option is not currently compatible with the
 *          tickless mode.
 */
#define CH_DBG_THREADS_PROFILING            FALSE

/** @} */

/*===========================================================================*/
/**
 * @name Kernel hooks
 * @{
 */
/*===========================================================================*/

/**
 * @brief   Threads descriptor structure extension.
 * @details User fields added to the end of the @p thread_t structure.
 */
#define CH_CFG_THREAD_EXTRA_FIELDS                                          \
  /* Add threads custom fields here.*/

/**
 * @brief   Threads initialization hook.
 * @details User initialization code added to the @p chThdInit() API.
 *
 * @note    It is invoked from within @p chThdInit() and implicitly from all
 *          the threads creation APIs.
 */
#define CH_CFG_THREAD_INIT_HOOK(tp) {                                       \
  /* Add threads initialization code here.*/                                \
}

/**
 * @brief   Threads finalization hook.
 * @details User finalization code added to the @p chThdExit() API.
 */
#define CH_CFG_THREAD_EXIT_HOOK(tp) {                                       \
  /* Add threads finalization code here.*/                                  \
}

/**
 * @brief   Context switch hook.
 * @details This hook is invoked just before switching between threads.
 */
#define CH_CFG_CONTEXT_SWITCH_HOOK(ntp, otp) {                              \
  /* Context switch code here.*/                                            \
}

/**
 * @brief   ISR enter hook.
 */
#define CH_CFG_IRQ_PROLOGUE_HOOK() {                                        \
  /* IRQ prologue code here.*/                                              \
}

/**
 * @brief   ISR exit hook.
 */
#define CH_CFG_IRQ_EPILOGUE_HOOK() {                                        \
  /* IRQ epilogue code here.*/                                              \
}

/**
 * @brief   Idle thread enter hook.
 * @note    This hook is invoked within a critical zone, no OS functions
 *          should be invoked from here.
 * @note    This macro can be used to activate a power saving mode.
 */
#define CH_CFG_IDLE_ENTER_HOOK() {                                          \
  /* Idle-enter code here.*/                                                \
}

/**
 * @brief   Idle thread leave hook.
 * @note    This hook is invoked within a critical zone, no OS functions
 *          should be invoked from here.
 * @note    This macro can be used to deactivate a power saving mode.
 */
#define CH_CFG_IDLE_LEAVE_HOOK() {                                          \
  /* Idle-leave code here.*/                                                \
}

/**
 * @brief   Idle Loop hook.
 * @details This hook is continuously invoked by the idle thread loop.
 */
#define CH_CFG_IDLE_LOOP_HOOK() {                                           \
  /* Idle loop code here.*/                                                 \
}

/**
 * @brief   System tick event hook.
 * @details This hook is invoked in the system tick handler immediately
 *          after processing the virtual timers queue.
 */
#define CH_CFG_SYSTEM_TICK_HOOK() {                                         \
  /* System tick event code here.*/                                         \
}

/**
 * @brief   System halt hook.
 * @details This hook is invoked in case to a system halting error before
 *          the system is halted.
 */
#define CH_CFG_SYSTEM_HALT_HOOK(reason) {                                   \
  /* System halt code here.*/                                               \
}

/**
 * @brief   Trace hook.
 * @details This hook is invoked each time a new record is written in the
 *          trace buffer.
 */
#define CH_CFG_TRACE_HOOK(tep) {                                            \
  /* Trace code here.*/                                                     \
}

/** @} */

/*===========================================================================*/
/* Port-specific settings (override port settings defaulted in chcore.h).    */
/*===========================================================================*/

#endif  /* CHCONF_H */

/** @} */
#n1582'>1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705 2706 2707 2708 2709 2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788 2789 2790 2791 2792 2793 2794 2795 2796 2797 2798 2799 2800 2801 2802 2803 2804 2805 2806 2807 2808 2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841 2842 2843 2844 2845 2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 2958 2959 2960 2961 2962 2963 2964 2965 2966 2967 2968 2969 2970 2971 2972 2973 2974 2975 2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029 3030 3031 3032 3033 3034 3035 3036 3037 3038 3039 3040 3041 3042 3043 3044 3045 3046 3047 3048 3049 3050 3051 3052 3053 3054 3055 3056 3057 3058 3059 3060 3061 3062 3063 3064 3065 3066 3067 3068 3069 3070 3071 3072 3073 3074 3075 3076 3077 3078 3079 3080 3081 3082 3083 3084 3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103 3104 3105 3106 3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132 3133 3134 3135 3136 3137 3138 3139 3140 3141 3142 3143 3144 3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209 3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236 3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247 3248 3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 3261 3262 3263 3264 3265 3266 3267 3268 3269 3270 3271 3272 3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331 3332 3333 3334 3335 3336 3337 3338 3339 3340 3341 3342 3343 3344 3345 3346 3347 3348 3349 3350 3351 3352 3353 3354 3355 3356 3357 3358 3359 3360 3361 3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380 3381 3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392 3393 3394 3395 3396 3397 3398 3399 3400 3401 3402 3403 3404 3405 3406 3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421 3422 3423 3424 3425 3426 3427 3428 3429 3430 3431 3432
You can find recipes for using Google Mock here. If you haven't yet,
please read the [ForDummies](V1_7_ForDummies.md) document first to make sure you understand
the basics.

**Note:** Google Mock lives in the `testing` name space. For
readability, it is recommended to write `using ::testing::Foo;` once in
your file before using the name `Foo` defined by Google Mock. We omit
such `using` statements in this page for brevity, but you should do it
in your own code.

# Creating Mock Classes #

## Mocking Private or Protected Methods ##

You must always put a mock method definition (`MOCK_METHOD*`) in a
`public:` section of the mock class, regardless of the method being
mocked being `public`, `protected`, or `private` in the base class.
This allows `ON_CALL` and `EXPECT_CALL` to reference the mock function
from outside of the mock class.  (Yes, C++ allows a subclass to change
the access level of a virtual function in the base class.)  Example:

```
class Foo {
 public:
  ...
  virtual bool Transform(Gadget* g) = 0;

 protected:
  virtual void Resume();

 private:
  virtual int GetTimeOut();
};

class MockFoo : public Foo {
 public:
  ...
  MOCK_METHOD1(Transform, bool(Gadget* g));

  // The following must be in the public section, even though the
  // methods are protected or private in the base class.
  MOCK_METHOD0(Resume, void());
  MOCK_METHOD0(GetTimeOut, int());
};
```

## Mocking Overloaded Methods ##

You can mock overloaded functions as usual. No special attention is required:

```
class Foo {
  ...

  // Must be virtual as we'll inherit from Foo.
  virtual ~Foo();

  // Overloaded on the types and/or numbers of arguments.
  virtual int Add(Element x);
  virtual int Add(int times, Element x);

  // Overloaded on the const-ness of this object.
  virtual Bar& GetBar();
  virtual const Bar& GetBar() const;
};

class MockFoo : public Foo {
  ...
  MOCK_METHOD1(Add, int(Element x));
  MOCK_METHOD2(Add, int(int times, Element x);

  MOCK_METHOD0(GetBar, Bar&());
  MOCK_CONST_METHOD0(GetBar, const Bar&());
};
```

**Note:** if you don't mock all versions of the overloaded method, the
compiler will give you a warning about some methods in the base class
being hidden. To fix that, use `using` to bring them in scope:

```
class MockFoo : public Foo {
  ...
  using Foo::Add;
  MOCK_METHOD1(Add, int(Element x));
  // We don't want to mock int Add(int times, Element x);
  ...
};
```

## Mocking Class Templates ##

To mock a class template, append `_T` to the `MOCK_*` macros:

```
template <typename Elem>
class StackInterface {
  ...
  // Must be virtual as we'll inherit from StackInterface.
  virtual ~StackInterface();

  virtual int GetSize() const = 0;
  virtual void Push(const Elem& x) = 0;
};

template <typename Elem>
class MockStack : public StackInterface<Elem> {
  ...
  MOCK_CONST_METHOD0_T(GetSize, int());
  MOCK_METHOD1_T(Push, void(const Elem& x));
};
```

## Mocking Nonvirtual Methods ##

Google Mock can mock non-virtual functions to be used in what we call _hi-perf
dependency injection_.

In this case, instead of sharing a common base class with the real
class, your mock class will be _unrelated_ to the real class, but
contain methods with the same signatures.  The syntax for mocking
non-virtual methods is the _same_ as mocking virtual methods:

```
// A simple packet stream class.  None of its members is virtual.
class ConcretePacketStream {
 public:
  void AppendPacket(Packet* new_packet);
  const Packet* GetPacket(size_t packet_number) const;
  size_t NumberOfPackets() const;
  ...
};

// A mock packet stream class.  It inherits from no other, but defines
// GetPacket() and NumberOfPackets().
class MockPacketStream {
 public:
  MOCK_CONST_METHOD1(GetPacket, const Packet*(size_t packet_number));
  MOCK_CONST_METHOD0(NumberOfPackets, size_t());
  ...
};
```

Note that the mock class doesn't define `AppendPacket()`, unlike the
real class. That's fine as long as the test doesn't need to call it.

Next, you need a way to say that you want to use
`ConcretePacketStream` in production code, and use `MockPacketStream`
in tests.  Since the functions are not virtual and the two classes are
unrelated, you must specify your choice at _compile time_ (as opposed
to run time).

One way to do it is to templatize your code that needs to use a packet
stream.  More specifically, you will give your code a template type
argument for the type of the packet stream.  In production, you will
instantiate your template with `ConcretePacketStream` as the type
argument.  In tests, you will instantiate the same template with
`MockPacketStream`.  For example, you may write:

```
template <class PacketStream>
void CreateConnection(PacketStream* stream) { ... }

template <class PacketStream>
class PacketReader {
 public:
  void ReadPackets(PacketStream* stream, size_t packet_num);
};
```

Then you can use `CreateConnection<ConcretePacketStream>()` and
`PacketReader<ConcretePacketStream>` in production code, and use
`CreateConnection<MockPacketStream>()` and
`PacketReader<MockPacketStream>` in tests.

```
  MockPacketStream mock_stream;
  EXPECT_CALL(mock_stream, ...)...;
  .. set more expectations on mock_stream ...
  PacketReader<MockPacketStream> reader(&mock_stream);
  ... exercise reader ...
```

## Mocking Free Functions ##

It's possible to use Google Mock to mock a free function (i.e. a
C-style function or a static method).  You just need to rewrite your
code to use an interface (abstract class).

Instead of calling a free function (say, `OpenFile`) directly,
introduce an interface for it and have a concrete subclass that calls
the free function:

```
class FileInterface {
 public:
  ...
  virtual bool Open(const char* path, const char* mode) = 0;
};

class File : public FileInterface {
 public:
  ...
  virtual bool Open(const char* path, const char* mode) {
    return OpenFile(path, mode);
  }
};
```

Your code should talk to `FileInterface` to open a file.  Now it's
easy to mock out the function.

This may seem much hassle, but in practice you often have multiple
related functions that you can put in the same interface, so the
per-function syntactic overhead will be much lower.

If you are concerned about the performance overhead incurred by
virtual functions, and profiling confirms your concern, you can
combine this with the recipe for [mocking non-virtual methods](#Mocking_Nonvirtual_Methods.md).

## The Nice, the Strict, and the Naggy ##

If a mock method has no `EXPECT_CALL` spec but is called, Google Mock
will print a warning about the "uninteresting call". The rationale is:

  * New methods may be added to an interface after a test is written. We shouldn't fail a test just because a method it doesn't know about is called.
  * However, this may also mean there's a bug in the test, so Google Mock shouldn't be silent either. If the user believes these calls are harmless, he can add an `EXPECT_CALL()` to suppress the warning.

However, sometimes you may want to suppress all "uninteresting call"
warnings, while sometimes you may want the opposite, i.e. to treat all
of them as errors. Google Mock lets you make the decision on a
per-mock-object basis.

Suppose your test uses a mock class `MockFoo`:

```
TEST(...) {
  MockFoo mock_foo;
  EXPECT_CALL(mock_foo, DoThis());
  ... code that uses mock_foo ...
}
```

If a method of `mock_foo` other than `DoThis()` is called, it will be
reported by Google Mock as a warning. However, if you rewrite your
test to use `NiceMock<MockFoo>` instead, the warning will be gone,
resulting in a cleaner test output:

```
using ::testing::NiceMock;

TEST(...) {
  NiceMock<MockFoo> mock_foo;
  EXPECT_CALL(mock_foo, DoThis());
  ... code that uses mock_foo ...
}
```

`NiceMock<MockFoo>` is a subclass of `MockFoo`, so it can be used
wherever `MockFoo` is accepted.

It also works if `MockFoo`'s constructor takes some arguments, as
`NiceMock<MockFoo>` "inherits" `MockFoo`'s constructors:

```
using ::testing::NiceMock;

TEST(...) {
  NiceMock<MockFoo> mock_foo(5, "hi");  // Calls MockFoo(5, "hi").
  EXPECT_CALL(mock_foo, DoThis());
  ... code that uses mock_foo ...
}
```

The usage of `StrictMock` is similar, except that it makes all
uninteresting calls failures:

```
using ::testing::StrictMock;

TEST(...) {
  StrictMock<MockFoo> mock_foo;
  EXPECT_CALL(mock_foo, DoThis());
  ... code that uses mock_foo ...

  // The test will fail if a method of mock_foo other than DoThis()
  // is called.
}
```

There are some caveats though (I don't like them just as much as the
next guy, but sadly they are side effects of C++'s limitations):

  1. `NiceMock<MockFoo>` and `StrictMock<MockFoo>` only work for mock methods defined using the `MOCK_METHOD*` family of macros **directly** in the `MockFoo` class. If a mock method is defined in a **base class** of `MockFoo`, the "nice" or "strict" modifier may not affect it, depending on the compiler. In particular, nesting `NiceMock` and `StrictMock` (e.g. `NiceMock<StrictMock<MockFoo> >`) is **not** supported.
  1. The constructors of the base mock (`MockFoo`) cannot have arguments passed by non-const reference, which happens to be banned by the [Google C++ style guide](http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml).
  1. During the constructor or destructor of `MockFoo`, the mock object is _not_ nice or strict.  This may cause surprises if the constructor or destructor calls a mock method on `this` object. (This behavior, however, is consistent with C++'s general rule: if a constructor or destructor calls a virtual method of `this` object, that method is treated as non-virtual.  In other words, to the base class's constructor or destructor, `this` object behaves like an instance of the base class, not the derived class.  This rule is required for safety.  Otherwise a base constructor may use members of a derived class before they are initialized, or a base destructor may use members of a derived class after they have been destroyed.)

Finally, you should be **very cautious** about when to use naggy or strict mocks, as they tend to make tests more brittle and harder to maintain. When you refactor your code without changing its externally visible behavior, ideally you should't need to update any tests. If your code interacts with a naggy mock, however, you may start to get spammed with warnings as the result of your change. Worse, if your code interacts with a strict mock, your tests may start to fail and you'll be forced to fix them. Our general recommendation is to use nice mocks (not yet the default) most of the time, use naggy mocks (the current default) when developing or debugging tests, and use strict mocks only as the last resort.

## Simplifying the Interface without Breaking Existing Code ##

Sometimes a method has a long list of arguments that is mostly
uninteresting. For example,

```
class LogSink {
 public:
  ...
  virtual void send(LogSeverity severity, const char* full_filename,
                    const char* base_filename, int line,
                    const struct tm* tm_time,
                    const char* message, size_t message_len) = 0;
};
```

This method's argument list is lengthy and hard to work with (let's
say that the `message` argument is not even 0-terminated). If we mock
it as is, using the mock will be awkward. If, however, we try to
simplify this interface, we'll need to fix all clients depending on
it, which is often infeasible.

The trick is to re-dispatch the method in the mock class:

```
class ScopedMockLog : public LogSink {
 public:
  ...
  virtual void send(LogSeverity severity, const char* full_filename,
                    const char* base_filename, int line, const tm* tm_time,
                    const char* message, size_t message_len) {
    // We are only interested in the log severity, full file name, and
    // log message.
    Log(severity, full_filename, std::string(message, message_len));
  }

  // Implements the mock method:
  //
  //   void Log(LogSeverity severity,
  //            const string& file_path,
  //            const string& message);
  MOCK_METHOD3(Log, void(LogSeverity severity, const string& file_path,
                         const string& message));
};
```

By defining a new mock method with a trimmed argument list, we make
the mock class much more user-friendly.

## Alternative to Mocking Concrete Classes ##

Often you may find yourself using classes that don't implement
interfaces. In order to test your code that uses such a class (let's
call it `Concrete`), you may be tempted to make the methods of
`Concrete` virtual and then mock it.

Try not to do that.

Making a non-virtual function virtual is a big decision. It creates an
extension point where subclasses can tweak your class' behavior. This
weakens your control on the class because now it's harder to maintain
the class' invariants. You should make a function virtual only when
there is a valid reason for a subclass to override it.

Mocking concrete classes directly is problematic as it creates a tight
coupling between the class and the tests - any small change in the
class may invalidate your tests and make test maintenance a pain.

To avoid such problems, many programmers have been practicing "coding
to interfaces": instead of talking to the `Concrete` class, your code
would define an interface and talk to it. Then you implement that
interface as an adaptor on top of `Concrete`. In tests, you can easily
mock that interface to observe how your code is doing.

This technique incurs some overhead:

  * You pay the cost of virtual function calls (usually not a problem).
  * There is more abstraction for the programmers to learn.

However, it can also bring significant benefits in addition to better
testability:

  * `Concrete`'s API may not fit your problem domain very well, as you may not be the only client it tries to serve. By designing your own interface, you have a chance to tailor it to your need - you may add higher-level functionalities, rename stuff, etc instead of just trimming the class. This allows you to write your code (user of the interface) in a more natural way, which means it will be more readable, more maintainable, and you'll be more productive.
  * If `Concrete`'s implementation ever has to change, you don't have to rewrite everywhere it is used. Instead, you can absorb the change in your implementation of the interface, and your other code and tests will be insulated from this change.

Some people worry that if everyone is practicing this technique, they
will end up writing lots of redundant code. This concern is totally
understandable. However, there are two reasons why it may not be the
case:

  * Different projects may need to use `Concrete` in different ways, so the best interfaces for them will be different. Therefore, each of them will have its own domain-specific interface on top of `Concrete`, and they will not be the same code.
  * If enough projects want to use the same interface, they can always share it, just like they have been sharing `Concrete`. You can check in the interface and the adaptor somewhere near `Concrete` (perhaps in a `contrib` sub-directory) and let many projects use it.

You need to weigh the pros and cons carefully for your particular
problem, but I'd like to assure you that the Java community has been
practicing this for a long time and it's a proven effective technique
applicable in a wide variety of situations. :-)

## Delegating Calls to a Fake ##

Some times you have a non-trivial fake implementation of an
interface. For example:

```
class Foo {
 public:
  virtual ~Foo() {}
  virtual char DoThis(int n) = 0;
  virtual void DoThat(const char* s, int* p) = 0;
};

class FakeFoo : public Foo {
 public:
  virtual char DoThis(int n) {
    return (n > 0) ? '+' :
        (n < 0) ? '-' : '0';
  }

  virtual void DoThat(const char* s, int* p) {
    *p = strlen(s);
  }
};
```

Now you want to mock this interface such that you can set expectations
on it. However, you also want to use `FakeFoo` for the default
behavior, as duplicating it in the mock object is, well, a lot of
work.

When you define the mock class using Google Mock, you can have it
delegate its default action to a fake class you already have, using
this pattern:

```
using ::testing::_;
using ::testing::Invoke;

class MockFoo : public Foo {
 public:
  // Normal mock method definitions using Google Mock.
  MOCK_METHOD1(DoThis, char(int n));
  MOCK_METHOD2(DoThat, void(const char* s, int* p));

  // Delegates the default actions of the methods to a FakeFoo object.
  // This must be called *before* the custom ON_CALL() statements.
  void DelegateToFake() {
    ON_CALL(*this, DoThis(_))
        .WillByDefault(Invoke(&fake_, &FakeFoo::DoThis));
    ON_CALL(*this, DoThat(_, _))
        .WillByDefault(Invoke(&fake_, &FakeFoo::DoThat));
  }
 private:
  FakeFoo fake_;  // Keeps an instance of the fake in the mock.
};
```

With that, you can use `MockFoo` in your tests as usual. Just remember
that if you don't explicitly set an action in an `ON_CALL()` or
`EXPECT_CALL()`, the fake will be called upon to do it:

```
using ::testing::_;

TEST(AbcTest, Xyz) {
  MockFoo foo;
  foo.DelegateToFake(); // Enables the fake for delegation.

  // Put your ON_CALL(foo, ...)s here, if any.

  // No action specified, meaning to use the default action.
  EXPECT_CALL(foo, DoThis(5));
  EXPECT_CALL(foo, DoThat(_, _));

  int n = 0;
  EXPECT_EQ('+', foo.DoThis(5));  // FakeFoo::DoThis() is invoked.
  foo.DoThat("Hi", &n);           // FakeFoo::DoThat() is invoked.
  EXPECT_EQ(2, n);
}
```

**Some tips:**

  * If you want, you can still override the default action by providing your own `ON_CALL()` or using `.WillOnce()` / `.WillRepeatedly()` in `EXPECT_CALL()`.
  * In `DelegateToFake()`, you only need to delegate the methods whose fake implementation you intend to use.
  * The general technique discussed here works for overloaded methods, but you'll need to tell the compiler which version you mean. To disambiguate a mock function (the one you specify inside the parentheses of `ON_CALL()`), see the "Selecting Between Overloaded Functions" section on this page; to disambiguate a fake function (the one you place inside `Invoke()`), use a `static_cast` to specify the function's type. For instance, if class `Foo` has methods `char DoThis(int n)` and `bool DoThis(double x) const`, and you want to invoke the latter, you need to write `Invoke(&fake_, static_cast<bool (FakeFoo::*)(double) const>(&FakeFoo::DoThis))` instead of `Invoke(&fake_, &FakeFoo::DoThis)` (The strange-looking thing inside the angled brackets of `static_cast` is the type of a function pointer to the second `DoThis()` method.).
  * Having to mix a mock and a fake is often a sign of something gone wrong. Perhaps you haven't got used to the interaction-based way of testing yet. Or perhaps your interface is taking on too many roles and should be split up. Therefore, **don't abuse this**. We would only recommend to do it as an intermediate step when you are refactoring your code.

Regarding the tip on mixing a mock and a fake, here's an example on
why it may be a bad sign: Suppose you have a class `System` for
low-level system operations. In particular, it does file and I/O
operations. And suppose you want to test how your code uses `System`
to do I/O, and you just want the file operations to work normally. If
you mock out the entire `System` class, you'll have to provide a fake
implementation for the file operation part, which suggests that
`System` is taking on too many roles.

Instead, you can define a `FileOps` interface and an `IOOps` interface
and split `System`'s functionalities into the two. Then you can mock
`IOOps` without mocking `FileOps`.

## Delegating Calls to a Real Object ##

When using testing doubles (mocks, fakes, stubs, and etc), sometimes
their behaviors will differ from those of the real objects. This
difference could be either intentional (as in simulating an error such
that you can test the error handling code) or unintentional. If your
mocks have different behaviors than the real objects by mistake, you
could end up with code that passes the tests but fails in production.

You can use the _delegating-to-real_ technique to ensure that your
mock has the same behavior as the real object while retaining the
ability to validate calls. This technique is very similar to the
delegating-to-fake technique, the difference being that we use a real
object instead of a fake. Here's an example:

```
using ::testing::_;
using ::testing::AtLeast;
using ::testing::Invoke;

class MockFoo : public Foo {
 public:
  MockFoo() {
    // By default, all calls are delegated to the real object.
    ON_CALL(*this, DoThis())
        .WillByDefault(Invoke(&real_, &Foo::DoThis));
    ON_CALL(*this, DoThat(_))
        .WillByDefault(Invoke(&real_, &Foo::DoThat));
    ...
  }
  MOCK_METHOD0(DoThis, ...);
  MOCK_METHOD1(DoThat, ...);
  ...
 private:
  Foo real_;
};
...

  MockFoo mock;

  EXPECT_CALL(mock, DoThis())
      .Times(3);
  EXPECT_CALL(mock, DoThat("Hi"))
      .Times(AtLeast(1));
  ... use mock in test ...
```

With this, Google Mock will verify that your code made the right calls
(with the right arguments, in the right order, called the right number
of times, etc), and a real object will answer the calls (so the
behavior will be the same as in production). This gives you the best
of both worlds.

## Delegating Calls to a Parent Class ##

Ideally, you should code to interfaces, whose methods are all pure
virtual. In reality, sometimes you do need to mock a virtual method
that is not pure (i.e, it already has an implementation). For example:

```
class Foo {
 public:
  virtual ~Foo();

  virtual void Pure(int n) = 0;
  virtual int Concrete(const char* str) { ... }
};

class MockFoo : public Foo {
 public:
  // Mocking a pure method.
  MOCK_METHOD1(Pure, void(int n));
  // Mocking a concrete method.  Foo::Concrete() is shadowed.
  MOCK_METHOD1(Concrete, int(const char* str));
};
```

Sometimes you may want to call `Foo::Concrete()` instead of
`MockFoo::Concrete()`. Perhaps you want to do it as part of a stub
action, or perhaps your test doesn't need to mock `Concrete()` at all
(but it would be oh-so painful to have to define a new mock class
whenever you don't need to mock one of its methods).

The trick is to leave a back door in your mock class for accessing the
real methods in the base class:

```
class MockFoo : public Foo {
 public:
  // Mocking a pure method.
  MOCK_METHOD1(Pure, void(int n));
  // Mocking a concrete method.  Foo::Concrete() is shadowed.
  MOCK_METHOD1(Concrete, int(const char* str));

  // Use this to call Concrete() defined in Foo.
  int FooConcrete(const char* str) { return Foo::Concrete(str); }
};
```

Now, you can call `Foo::Concrete()` inside an action by:

```
using ::testing::_;
using ::testing::Invoke;
...
  EXPECT_CALL(foo, Concrete(_))
      .WillOnce(Invoke(&foo, &MockFoo::FooConcrete));
```

or tell the mock object that you don't want to mock `Concrete()`:

```
using ::testing::Invoke;
...
  ON_CALL(foo, Concrete(_))
      .WillByDefault(Invoke(&foo, &MockFoo::FooConcrete));
```

(Why don't we just write `Invoke(&foo, &Foo::Concrete)`? If you do
that, `MockFoo::Concrete()` will be called (and cause an infinite
recursion) since `Foo::Concrete()` is virtual. That's just how C++
works.)

# Using Matchers #

## Matching Argument Values Exactly ##

You can specify exactly which arguments a mock method is expecting:

```
using ::testing::Return;
...
  EXPECT_CALL(foo, DoThis(5))
      .WillOnce(Return('a'));
  EXPECT_CALL(foo, DoThat("Hello", bar));
```

## Using Simple Matchers ##

You can use matchers to match arguments that have a certain property:

```
using ::testing::Ge;
using ::testing::NotNull;
using ::testing::Return;
...
  EXPECT_CALL(foo, DoThis(Ge(5)))  // The argument must be >= 5.
      .WillOnce(Return('a'));
  EXPECT_CALL(foo, DoThat("Hello", NotNull()));
  // The second argument must not be NULL.
```

A frequently used matcher is `_`, which matches anything:

```
using ::testing::_;
using ::testing::NotNull;
...
  EXPECT_CALL(foo, DoThat(_, NotNull()));
```

## Combining Matchers ##

You can build complex matchers from existing ones using `AllOf()`,
`AnyOf()`, and `Not()`:

```
using ::testing::AllOf;
using ::testing::Gt;
using ::testing::HasSubstr;
using ::testing::Ne;
using ::testing::Not;
...
  // The argument must be > 5 and != 10.
  EXPECT_CALL(foo, DoThis(AllOf(Gt(5),
                                Ne(10))));

  // The first argument must not contain sub-string "blah".
  EXPECT_CALL(foo, DoThat(Not(HasSubstr("blah")),
                          NULL));
```

## Casting Matchers ##

Google Mock matchers are statically typed, meaning that the compiler
can catch your mistake if you use a matcher of the wrong type (for
example, if you use `Eq(5)` to match a `string` argument). Good for
you!

Sometimes, however, you know what you're doing and want the compiler
to give you some slack. One example is that you have a matcher for
`long` and the argument you want to match is `int`. While the two
types aren't exactly the same, there is nothing really wrong with
using a `Matcher<long>` to match an `int` - after all, we can first
convert the `int` argument to a `long` before giving it to the
matcher.

To support this need, Google Mock gives you the
`SafeMatcherCast<T>(m)` function. It casts a matcher `m` to type
`Matcher<T>`. To ensure safety, Google Mock checks that (let `U` be the
type `m` accepts):

  1. Type `T` can be implicitly cast to type `U`;
  1. When both `T` and `U` are built-in arithmetic types (`bool`, integers, and floating-point numbers), the conversion from `T` to `U` is not lossy (in other words, any value representable by `T` can also be represented by `U`); and
  1. When `U` is a reference, `T` must also be a reference (as the underlying matcher may be interested in the address of the `U` value).

The code won't compile if any of these conditions isn't met.

Here's one example:

```
using ::testing::SafeMatcherCast;

// A base class and a child class.
class Base { ... };
class Derived : public Base { ... };

class MockFoo : public Foo {
 public:
  MOCK_METHOD1(DoThis, void(Derived* derived));
};
...

  MockFoo foo;
  // m is a Matcher<Base*> we got from somewhere.
  EXPECT_CALL(foo, DoThis(SafeMatcherCast<Derived*>(m)));
```

If you find `SafeMatcherCast<T>(m)` too limiting, you can use a similar
function `MatcherCast<T>(m)`. The difference is that `MatcherCast` works
as long as you can `static_cast` type `T` to type `U`.

`MatcherCast` essentially lets you bypass C++'s type system
(`static_cast` isn't always safe as it could throw away information,
for example), so be careful not to misuse/abuse it.

## Selecting Between Overloaded Functions ##

If you expect an overloaded function to be called, the compiler may
need some help on which overloaded version it is.

To disambiguate functions overloaded on the const-ness of this object,
use the `Const()` argument wrapper.

```
using ::testing::ReturnRef;

class MockFoo : public Foo {
  ...
  MOCK_METHOD0(GetBar, Bar&());
  MOCK_CONST_METHOD0(GetBar, const Bar&());
};
...

  MockFoo foo;
  Bar bar1, bar2;
  EXPECT_CALL(foo, GetBar())         // The non-const GetBar().
      .WillOnce(ReturnRef(bar1));
  EXPECT_CALL(Const(foo), GetBar())  // The const GetBar().
      .WillOnce(ReturnRef(bar2));
```

(`Const()` is defined by Google Mock and returns a `const` reference
to its argument.)

To disambiguate overloaded functions with the same number of arguments
but different argument types, you may need to specify the exact type
of a matcher, either by wrapping your matcher in `Matcher<type>()`, or
using a matcher whose type is fixed (`TypedEq<type>`, `An<type>()`,
etc):

```
using ::testing::An;
using ::testing::Lt;
using ::testing::Matcher;
using ::testing::TypedEq;

class MockPrinter : public Printer {
 public:
  MOCK_METHOD1(Print, void(int n));
  MOCK_METHOD1(Print, void(char c));
};

TEST(PrinterTest, Print) {
  MockPrinter printer;

  EXPECT_CALL(printer, Print(An<int>()));            // void Print(int);
  EXPECT_CALL(printer, Print(Matcher<int>(Lt(5))));  // void Print(int);
  EXPECT_CALL(printer, Print(TypedEq<char>('a')));   // void Print(char);

  printer.Print(3);
  printer.Print(6);
  printer.Print('a');
}
```

## Performing Different Actions Based on the Arguments ##

When a mock method is called, the _last_ matching expectation that's
still active will be selected (think "newer overrides older"). So, you
can make a method do different things depending on its argument values
like this:

```
using ::testing::_;
using ::testing::Lt;
using ::testing::Return;
...
  // The default case.
  EXPECT_CALL(foo, DoThis(_))
      .WillRepeatedly(Return('b'));

  // The more specific case.
  EXPECT_CALL(foo, DoThis(Lt(5)))
      .WillRepeatedly(Return('a'));
```

Now, if `foo.DoThis()` is called with a value less than 5, `'a'` will
be returned; otherwise `'b'` will be returned.

## Matching Multiple Arguments as a Whole ##

Sometimes it's not enough to match the arguments individually. For
example, we may want to say that the first argument must be less than
the second argument. The `With()` clause allows us to match
all arguments of a mock function as a whole. For example,

```
using ::testing::_;
using ::testing::Lt;
using ::testing::Ne;
...
  EXPECT_CALL(foo, InRange(Ne(0), _))
      .With(Lt());
```

says that the first argument of `InRange()` must not be 0, and must be
less than the second argument.

The expression inside `With()` must be a matcher of type
`Matcher<tr1::tuple<A1, ..., An> >`, where `A1`, ..., `An` are the
types of the function arguments.

You can also write `AllArgs(m)` instead of `m` inside `.With()`. The
two forms are equivalent, but `.With(AllArgs(Lt()))` is more readable
than `.With(Lt())`.

You can use `Args<k1, ..., kn>(m)` to match the `n` selected arguments
(as a tuple) against `m`. For example,

```
using ::testing::_;
using ::testing::AllOf;
using ::testing::Args;
using ::testing::Lt;
...
  EXPECT_CALL(foo, Blah(_, _, _))
      .With(AllOf(Args<0, 1>(Lt()), Args<1, 2>(Lt())));
```

says that `Blah()` will be called with arguments `x`, `y`, and `z` where
`x < y < z`.

As a convenience and example, Google Mock provides some matchers for
2-tuples, including the `Lt()` matcher above. See the [CheatSheet](V1_7_CheatSheet.md) for
the complete list.

Note that if you want to pass the arguments to a predicate of your own
(e.g. `.With(Args<0, 1>(Truly(&MyPredicate)))`), that predicate MUST be
written to take a `tr1::tuple` as its argument; Google Mock will pass the `n`
selected arguments as _one_ single tuple to the predicate.

## Using Matchers as Predicates ##

Have you noticed that a matcher is just a fancy predicate that also
knows how to describe itself? Many existing algorithms take predicates
as arguments (e.g. those defined in STL's `<algorithm>` header), and
it would be a shame if Google Mock matchers are not allowed to
participate.

Luckily, you can use a matcher where a unary predicate functor is
expected by wrapping it inside the `Matches()` function. For example,

```
#include <algorithm>
#include <vector>

std::vector<int> v;
...
// How many elements in v are >= 10?
const int count = count_if(v.begin(), v.end(), Matches(Ge(10)));
```

Since you can build complex matchers from simpler ones easily using
Google Mock, this gives you a way to conveniently construct composite
predicates (doing the same using STL's `<functional>` header is just
painful). For example, here's a predicate that's satisfied by any
number that is >= 0, <= 100, and != 50:

```
Matches(AllOf(Ge(0), Le(100), Ne(50)))
```

## Using Matchers in Google Test Assertions ##

Since matchers are basically predicates that also know how to describe
themselves, there is a way to take advantage of them in
[Google Test](http://code.google.com/p/googletest/) assertions. It's
called `ASSERT_THAT` and `EXPECT_THAT`:

```
  ASSERT_THAT(value, matcher);  // Asserts that value matches matcher.
  EXPECT_THAT(value, matcher);  // The non-fatal version.
```

For example, in a Google Test test you can write:

```
#include "gmock/gmock.h"

using ::testing::AllOf;
using ::testing::Ge;
using ::testing::Le;
using ::testing::MatchesRegex;
using ::testing::StartsWith;
...

  EXPECT_THAT(Foo(), StartsWith("Hello"));
  EXPECT_THAT(Bar(), MatchesRegex("Line \\d+"));
  ASSERT_THAT(Baz(), AllOf(Ge(5), Le(10)));
```

which (as you can probably guess) executes `Foo()`, `Bar()`, and
`Baz()`, and verifies that:

  * `Foo()` returns a string that starts with `"Hello"`.
  * `Bar()` returns a string that matches regular expression `"Line \\d+"`.
  * `Baz()` returns a number in the range [5, 10].

The nice thing about these macros is that _they read like
English_. They generate informative messages too. For example, if the
first `EXPECT_THAT()` above fails, the message will be something like:

```
Value of: Foo()
  Actual: "Hi, world!"
Expected: starts with "Hello"
```

**Credit:** The idea of `(ASSERT|EXPECT)_THAT` was stolen from the
[Hamcrest](http://code.google.com/p/hamcrest/) project, which adds
`assertThat()` to JUnit.

## Using Predicates as Matchers ##

Google Mock provides a built-in set of matchers. In case you find them
lacking, you can use an arbitray unary predicate function or functor
as a matcher - as long as the predicate accepts a value of the type
you want. You do this by wrapping the predicate inside the `Truly()`
function, for example:

```
using ::testing::Truly;

int IsEven(int n) { return (n % 2) == 0 ? 1 : 0; }
...

  // Bar() must be called with an even number.
  EXPECT_CALL(foo, Bar(Truly(IsEven)));
```

Note that the predicate function / functor doesn't have to return
`bool`. It works as long as the return value can be used as the
condition in statement `if (condition) ...`.

## Matching Arguments that Are Not Copyable ##

When you do an `EXPECT_CALL(mock_obj, Foo(bar))`, Google Mock saves
away a copy of `bar`. When `Foo()` is called later, Google Mock
compares the argument to `Foo()` with the saved copy of `bar`. This
way, you don't need to worry about `bar` being modified or destroyed
after the `EXPECT_CALL()` is executed. The same is true when you use
matchers like `Eq(bar)`, `Le(bar)`, and so on.

But what if `bar` cannot be copied (i.e. has no copy constructor)? You
could define your own matcher function and use it with `Truly()`, as
the previous couple of recipes have shown. Or, you may be able to get
away from it if you can guarantee that `bar` won't be changed after
the `EXPECT_CALL()` is executed. Just tell Google Mock that it should
save a reference to `bar`, instead of a copy of it. Here's how:

```
using ::testing::Eq;
using ::testing::ByRef;
using ::testing::Lt;
...
  // Expects that Foo()'s argument == bar.
  EXPECT_CALL(mock_obj, Foo(Eq(ByRef(bar))));

  // Expects that Foo()'s argument < bar.
  EXPECT_CALL(mock_obj, Foo(Lt(ByRef(bar))));
```

Remember: if you do this, don't change `bar` after the
`EXPECT_CALL()`, or the result is undefined.

## Validating a Member of an Object ##

Often a mock function takes a reference to object as an argument. When
matching the argument, you may not want to compare the entire object
against a fixed object, as that may be over-specification. Instead,
you may need to validate a certain member variable or the result of a
certain getter method of the object. You can do this with `Field()`
and `Property()`. More specifically,

```
Field(&Foo::bar, m)
```

is a matcher that matches a `Foo` object whose `bar` member variable
satisfies matcher `m`.

```
Property(&Foo::baz, m)
```

is a matcher that matches a `Foo` object whose `baz()` method returns
a value that satisfies matcher `m`.

For example:

> | `Field(&Foo::number, Ge(3))` | Matches `x` where `x.number >= 3`. |
|:-----------------------------|:-----------------------------------|
> | `Property(&Foo::name, StartsWith("John "))` | Matches `x` where `x.name()` starts with `"John "`. |

Note that in `Property(&Foo::baz, ...)`, method `baz()` must take no
argument and be declared as `const`.

BTW, `Field()` and `Property()` can also match plain pointers to
objects. For instance,

```
Field(&Foo::number, Ge(3))
```

matches a plain pointer `p` where `p->number >= 3`. If `p` is `NULL`,
the match will always fail regardless of the inner matcher.

What if you want to validate more than one members at the same time?
Remember that there is `AllOf()`.

## Validating the Value Pointed to by a Pointer Argument ##

C++ functions often take pointers as arguments. You can use matchers
like `IsNull()`, `NotNull()`, and other comparison matchers to match a
pointer, but what if you want to make sure the value _pointed to_ by
the pointer, instead of the pointer itself, has a certain property?
Well, you can use the `Pointee(m)` matcher.

`Pointee(m)` matches a pointer iff `m` matches the value the pointer
points to. For example:

```
using ::testing::Ge;
using ::testing::Pointee;
...
  EXPECT_CALL(foo, Bar(Pointee(Ge(3))));
```

expects `foo.Bar()` to be called with a pointer that points to a value
greater than or equal to 3.

One nice thing about `Pointee()` is that it treats a `NULL` pointer as
a match failure, so you can write `Pointee(m)` instead of

```
  AllOf(NotNull(), Pointee(m))
```

without worrying that a `NULL` pointer will crash your test.

Also, did we tell you that `Pointee()` works with both raw pointers
**and** smart pointers (`linked_ptr`, `shared_ptr`, `scoped_ptr`, and
etc)?

What if you have a pointer to pointer? You guessed it - you can use
nested `Pointee()` to probe deeper inside the value. For example,
`Pointee(Pointee(Lt(3)))` matches a pointer that points to a pointer
that points to a number less than 3 (what a mouthful...).

## Testing a Certain Property of an Object ##

Sometimes you want to specify that an object argument has a certain
property, but there is no existing matcher that does this. If you want
good error messages, you should define a matcher. If you want to do it
quick and dirty, you could get away with writing an ordinary function.

Let's say you have a mock function that takes an object of type `Foo`,
which has an `int bar()` method and an `int baz()` method, and you
want to constrain that the argument's `bar()` value plus its `baz()`
value is a given number. Here's how you can define a matcher to do it:

```
using ::testing::MatcherInterface;
using ::testing::MatchResultListener;

class BarPlusBazEqMatcher : public MatcherInterface<const Foo&> {
 public:
  explicit BarPlusBazEqMatcher(int expected_sum)
      : expected_sum_(expected_sum) {}

  virtual bool MatchAndExplain(const Foo& foo,
                               MatchResultListener* listener) const {
    return (foo.bar() + foo.baz()) == expected_sum_;
  }

  virtual void DescribeTo(::std::ostream* os) const {
    *os << "bar() + baz() equals " << expected_sum_;
  }

  virtual void DescribeNegationTo(::std::ostream* os) const {
    *os << "bar() + baz() does not equal " << expected_sum_;
  }
 private:
  const int expected_sum_;
};

inline Matcher<const Foo&> BarPlusBazEq(int expected_sum) {
  return MakeMatcher(new BarPlusBazEqMatcher(expected_sum));
}

...

  EXPECT_CALL(..., DoThis(BarPlusBazEq(5)))...;
```

## Matching Containers ##

Sometimes an STL container (e.g. list, vector, map, ...) is passed to
a mock function and you may want to validate it. Since most STL
containers support the `==` operator, you can write
`Eq(expected_container)` or simply `expected_container` to match a
container exactly.

Sometimes, though, you may want to be more flexible (for example, the
first element must be an exact match, but the second element can be
any positive number, and so on). Also, containers used in tests often
have a small number of elements, and having to define the expected
container out-of-line is a bit of a hassle.

You can use the `ElementsAre()` or `UnorderedElementsAre()` matcher in
such cases:

```
using ::testing::_;
using ::testing::ElementsAre;
using ::testing::Gt;
...

  MOCK_METHOD1(Foo, void(const vector<int>& numbers));
...

  EXPECT_CALL(mock, Foo(ElementsAre(1, Gt(0), _, 5)));
```

The above matcher says that the container must have 4 elements, which
must be 1, greater than 0, anything, and 5 respectively.

If you instead write:

```
using ::testing::_;
using ::testing::Gt;
using ::testing::UnorderedElementsAre;
...

  MOCK_METHOD1(Foo, void(const vector<int>& numbers));
...

  EXPECT_CALL(mock, Foo(UnorderedElementsAre(1, Gt(0), _, 5)));
```

It means that the container must have 4 elements, which under some
permutation must be 1, greater than 0, anything, and 5 respectively.

`ElementsAre()` and `UnorderedElementsAre()` are overloaded to take 0
to 10 arguments. If more are needed, you can place them in a C-style
array and use `ElementsAreArray()` or `UnorderedElementsAreArray()`
instead:

```
using ::testing::ElementsAreArray;
...

  // ElementsAreArray accepts an array of element values.
  const int expected_vector1[] = { 1, 5, 2, 4, ... };
  EXPECT_CALL(mock, Foo(ElementsAreArray(expected_vector1)));

  // Or, an array of element matchers.
  Matcher<int> expected_vector2 = { 1, Gt(2), _, 3, ... };
  EXPECT_CALL(mock, Foo(ElementsAreArray(expected_vector2)));
```

In case the array needs to be dynamically created (and therefore the
array size cannot be inferred by the compiler), you can give
`ElementsAreArray()` an additional argument to specify the array size:

```
using ::testing::ElementsAreArray;
...
  int* const expected_vector3 = new int[count];
  ... fill expected_vector3 with values ...
  EXPECT_CALL(mock, Foo(ElementsAreArray(expected_vector3, count)));
```

**Tips:**

  * `ElementsAre*()` can be used to match _any_ container that implements the STL iterator pattern (i.e. it has a `const_iterator` type and supports `begin()/end()`), not just the ones defined in STL. It will even work with container types yet to be written - as long as they follows the above pattern.
  * You can use nested `ElementsAre*()` to match nested (multi-dimensional) containers.
  * If the container is passed by pointer instead of by reference, just write `Pointee(ElementsAre*(...))`.
  * The order of elements _matters_ for `ElementsAre*()`. Therefore don't use it with containers whose element order is undefined (e.g. `hash_map`).

## Sharing Matchers ##

Under the hood, a Google Mock matcher object consists of a pointer to
a ref-counted implementation object. Copying matchers is allowed and
very efficient, as only the pointer is copied. When the last matcher
that references the implementation object dies, the implementation
object will be deleted.

Therefore, if you have some complex matcher that you want to use again
and again, there is no need to build it everytime. Just assign it to a
matcher variable and use that variable repeatedly! For example,

```
  Matcher<int> in_range = AllOf(Gt(5), Le(10));
  ... use in_range as a matcher in multiple EXPECT_CALLs ...
```

# Setting Expectations #

## Knowing When to Expect ##

`ON_CALL` is likely the single most under-utilized construct in Google Mock.

There are basically two constructs for defining the behavior of a mock object: `ON_CALL` and `EXPECT_CALL`. The difference? `ON_CALL` defines what happens when a mock method is called, but _doesn't imply any expectation on the method being called._ `EXPECT_CALL` not only defines the behavior, but also sets an expectation that _the method will be called with the given arguments, for the given number of times_ (and _in the given order_ when you specify the order too).

Since `EXPECT_CALL` does more, isn't it better than `ON_CALL`? Not really. Every `EXPECT_CALL` adds a constraint on the behavior of the code under test. Having more constraints than necessary is _baaad_ - even worse than not having enough constraints.

This may be counter-intuitive. How could tests that verify more be worse than tests that verify less? Isn't verification the whole point of tests?

The answer, lies in _what_ a test should verify. **A good test verifies the contract of the code.** If a test over-specifies, it doesn't leave enough freedom to the implementation. As a result, changing the implementation without breaking the contract (e.g. refactoring and optimization), which should be perfectly fine to do, can break such tests. Then you have to spend time fixing them, only to see them broken again the next time the implementation is changed.

Keep in mind that one doesn't have to verify more than one property in one test. In fact, **it's a good style to verify only one thing in one test.** If you do that, a bug will likely break only one or two tests instead of dozens (which case would you rather debug?). If you are also in the habit of giving tests descriptive names that tell what they verify, you can often easily guess what's wrong just from the test log itself.

So use `ON_CALL` by default, and only use `EXPECT_CALL` when you actually intend to verify that the call is made. For example, you may have a bunch of `ON_CALL`s in your test fixture to set the common mock behavior shared by all tests in the same group, and write (scarcely) different `EXPECT_CALL`s in different `TEST_F`s to verify different aspects of the code's behavior. Compared with the style where each `TEST` has many `EXPECT_CALL`s, this leads to tests that are more resilient to implementational changes (and thus less likely to require maintenance) and makes the intent of the tests more obvious (so they are easier to maintain when you do need to maintain them).

## Ignoring Uninteresting Calls ##

If you are not interested in how a mock method is called, just don't
say anything about it. In this case, if the method is ever called,
Google Mock will perform its default action to allow the test program
to continue. If you are not happy with the default action taken by
Google Mock, you can override it using `DefaultValue<T>::Set()`
(described later in this document) or `ON_CALL()`.

Please note that once you expressed interest in a particular mock
method (via `EXPECT_CALL()`), all invocations to it must match some
expectation. If this function is called but the arguments don't match
any `EXPECT_CALL()` statement, it will be an error.

## Disallowing Unexpected Calls ##

If a mock method shouldn't be called at all, explicitly say so:

```
using ::testing::_;
...
  EXPECT_CALL(foo, Bar(_))
      .Times(0);
```

If some calls to the method are allowed, but the rest are not, just
list all the expected calls:

```
using ::testing::AnyNumber;
using ::testing::Gt;
...
  EXPECT_CALL(foo, Bar(5));
  EXPECT_CALL(foo, Bar(Gt(10)))
      .Times(AnyNumber());
```

A call to `foo.Bar()` that doesn't match any of the `EXPECT_CALL()`
statements will be an error.

## Expecting Ordered Calls ##

Although an `EXPECT_CALL()` statement defined earlier takes precedence
when Google Mock tries to match a function call with an expectation,
by default calls don't have to happen in the order `EXPECT_CALL()`
statements are written. For example, if the arguments match the
matchers in the third `EXPECT_CALL()`, but not those in the first two,
then the third expectation will be used.

If you would rather have all calls occur in the order of the
expectations, put the `EXPECT_CALL()` statements in a block where you
define a variable of type `InSequence`:

```
  using ::testing::_;
  using ::testing::InSequence;

  {
    InSequence s;

    EXPECT_CALL(foo, DoThis(5));
    EXPECT_CALL(bar, DoThat(_))
        .Times(2);
    EXPECT_CALL(foo, DoThis(6));
  }
```

In this example, we expect a call to `foo.DoThis(5)`, followed by two
calls to `bar.DoThat()` where the argument can be anything, which are
in turn followed by a call to `foo.DoThis(6)`. If a call occurred
out-of-order, Google Mock will report an error.

## Expecting Partially Ordered Calls ##

Sometimes requiring everything to occur in a predetermined order can
lead to brittle tests. For example, we may care about `A` occurring
before both `B` and `C`, but aren't interested in the relative order
of `B` and `C`. In this case, the test should reflect our real intent,
instead of being overly constraining.

Google Mock allows you to impose an arbitrary DAG (directed acyclic
graph) on the calls. One way to express the DAG is to use the
[After](http://code.google.com/p/googlemock/wiki/V1_7_CheatSheet#The_After_Clause) clause of `EXPECT_CALL`.

Another way is via the `InSequence()` clause (not the same as the
`InSequence` class), which we borrowed from jMock 2. It's less
flexible than `After()`, but more convenient when you have long chains
of sequential calls, as it doesn't require you to come up with
different names for the expectations in the chains.  Here's how it
works:

If we view `EXPECT_CALL()` statements as nodes in a graph, and add an
edge from node A to node B wherever A must occur before B, we can get
a DAG. We use the term "sequence" to mean a directed path in this
DAG. Now, if we decompose the DAG into sequences, we just need to know
which sequences each `EXPECT_CALL()` belongs to in order to be able to
reconstruct the orginal DAG.

So, to specify the partial order on the expectations we need to do two
things: first to define some `Sequence` objects, and then for each
`EXPECT_CALL()` say which `Sequence` objects it is part
of. Expectations in the same sequence must occur in the order they are
written. For example,

```
  using ::testing::Sequence;

  Sequence s1, s2;

  EXPECT_CALL(foo, A())
      .InSequence(s1, s2);
  EXPECT_CALL(bar, B())
      .InSequence(s1);
  EXPECT_CALL(bar, C())
      .InSequence(s2);
  EXPECT_CALL(foo, D())
      .InSequence(s2);
```

specifies the following DAG (where `s1` is `A -> B`, and `s2` is `A ->
C -> D`):

```
       +---> B
       |
  A ---|
       |
       +---> C ---> D
```

This means that A must occur before B and C, and C must occur before
D. There's no restriction about the order other than these.

## Controlling When an Expectation Retires ##

When a mock method is called, Google Mock only consider expectations
that are still active. An expectation is active when created, and
becomes inactive (aka _retires_) when a call that has to occur later
has occurred. For example, in

```
  using ::testing::_;
  using ::testing::Sequence;

  Sequence s1, s2;

  EXPECT_CALL(log, Log(WARNING, _, "File too large."))     // #1
      .Times(AnyNumber())
      .InSequence(s1, s2);
  EXPECT_CALL(log, Log(WARNING, _, "Data set is empty."))  // #2
      .InSequence(s1);
  EXPECT_CALL(log, Log(WARNING, _, "User not found."))     // #3
      .InSequence(s2);
```

as soon as either #2 or #3 is matched, #1 will retire. If a warning
`"File too large."` is logged after this, it will be an error.

Note that an expectation doesn't retire automatically when it's
saturated. For example,

```
using ::testing::_;
...
  EXPECT_CALL(log, Log(WARNING, _, _));                  // #1
  EXPECT_CALL(log, Log(WARNING, _, "File too large."));  // #2
```

says that there will be exactly one warning with the message `"File
too large."`. If the second warning contains this message too, #2 will
match again and result in an upper-bound-violated error.

If this is not what you want, you can ask an expectation to retire as
soon as it becomes saturated:

```
using ::testing::_;
...
  EXPECT_CALL(log, Log(WARNING, _, _));                 // #1
  EXPECT_CALL(log, Log(WARNING, _, "File too large."))  // #2
      .RetiresOnSaturation();
```

Here #2 can be used only once, so if you have two warnings with the
message `"File too large."`, the first will match #2 and the second
will match #1 - there will be no error.

# Using Actions #

## Returning References from Mock Methods ##

If a mock function's return type is a reference, you need to use
`ReturnRef()` instead of `Return()` to return a result:

```
using ::testing::ReturnRef;

class MockFoo : public Foo {
 public:
  MOCK_METHOD0(GetBar, Bar&());
};
...

  MockFoo foo;
  Bar bar;
  EXPECT_CALL(foo, GetBar())
      .WillOnce(ReturnRef(bar));
```

## Returning Live Values from Mock Methods ##

The `Return(x)` action saves a copy of `x` when the action is
_created_, and always returns the same value whenever it's
executed. Sometimes you may want to instead return the _live_ value of
`x` (i.e. its value at the time when the action is _executed_.).

If the mock function's return type is a reference, you can do it using
`ReturnRef(x)`, as shown in the previous recipe ("Returning References
from Mock Methods"). However, Google Mock doesn't let you use
`ReturnRef()` in a mock function whose return type is not a reference,
as doing that usually indicates a user error. So, what shall you do?

You may be tempted to try `ByRef()`:

```
using testing::ByRef;
using testing::Return;

class MockFoo : public Foo {
 public:
  MOCK_METHOD0(GetValue, int());
};
...
  int x = 0;
  MockFoo foo;
  EXPECT_CALL(foo, GetValue())
      .WillRepeatedly(Return(ByRef(x)));
  x = 42;
  EXPECT_EQ(42, foo.GetValue());
```

Unfortunately, it doesn't work here. The above code will fail with error:

```
Value of: foo.GetValue()
  Actual: 0
Expected: 42
```

The reason is that `Return(value)` converts `value` to the actual
return type of the mock function at the time when the action is
_created_, not when it is _executed_. (This behavior was chosen for
the action to be safe when `value` is a proxy object that references
some temporary objects.) As a result, `ByRef(x)` is converted to an
`int` value (instead of a `const int&`) when the expectation is set,
and `Return(ByRef(x))` will always return 0.

`ReturnPointee(pointer)` was provided to solve this problem
specifically. It returns the value pointed to by `pointer` at the time
the action is _executed_:

```
using testing::ReturnPointee;
...
  int x = 0;
  MockFoo foo;
  EXPECT_CALL(foo, GetValue())
      .WillRepeatedly(ReturnPointee(&x));  // Note the & here.
  x = 42;
  EXPECT_EQ(42, foo.GetValue());  // This will succeed now.
```

## Combining Actions ##

Want to do more than one thing when a function is called? That's
fine. `DoAll()` allow you to do sequence of actions every time. Only
the return value of the last action in the sequence will be used.

```
using ::testing::DoAll;

class MockFoo : public Foo {
 public:
  MOCK_METHOD1(Bar, bool(int n));
};
...

  EXPECT_CALL(foo, Bar(_))
      .WillOnce(DoAll(action_1,
                      action_2,
                      ...
                      action_n));
```

## Mocking Side Effects ##

Sometimes a method exhibits its effect not via returning a value but
via side effects. For example, it may change some global state or
modify an output argument. To mock side effects, in general you can
define your own action by implementing `::testing::ActionInterface`.

If all you need to do is to change an output argument, the built-in
`SetArgPointee()` action is convenient:

```
using ::testing::SetArgPointee;

class MockMutator : public Mutator {
 public:
  MOCK_METHOD2(Mutate, void(bool mutate, int* value));
  ...
};
...

  MockMutator mutator;
  EXPECT_CALL(mutator, Mutate(true, _))
      .WillOnce(SetArgPointee<1>(5));
```

In this example, when `mutator.Mutate()` is called, we will assign 5
to the `int` variable pointed to by argument #1
(0-based).

`SetArgPointee()` conveniently makes an internal copy of the
value you pass to it, removing the need to keep the value in scope and
alive. The implication however is that the value must have a copy
constructor and assignment operator.

If the mock method also needs to return a value as well, you can chain
`SetArgPointee()` with `Return()` using `DoAll()`:

```
using ::testing::_;
using ::testing::Return;
using ::testing::SetArgPointee;

class MockMutator : public Mutator {
 public:
  ...
  MOCK_METHOD1(MutateInt, bool(int* value));
};
...

  MockMutator mutator;
  EXPECT_CALL(mutator, MutateInt(_))
      .WillOnce(DoAll(SetArgPointee<0>(5),
                      Return(true)));
```

If the output argument is an array, use the
`SetArrayArgument<N>(first, last)` action instead. It copies the
elements in source range `[first, last)` to the array pointed to by
the `N`-th (0-based) argument:

```
using ::testing::NotNull;
using ::testing::SetArrayArgument;

class MockArrayMutator : public ArrayMutator {
 public:
  MOCK_METHOD2(Mutate, void(int* values, int num_values));
  ...
};
...

  MockArrayMutator mutator;
  int values[5] = { 1, 2, 3, 4, 5 };
  EXPECT_CALL(mutator, Mutate(NotNull(), 5))
      .WillOnce(SetArrayArgument<0>(values, values + 5));
```

This also works when the argument is an output iterator:

```
using ::testing::_;
using ::testing::SeArrayArgument;

class MockRolodex : public Rolodex {
 public:
  MOCK_METHOD1(GetNames, void(std::back_insert_iterator<vector<string> >));
  ...
};
...

  MockRolodex rolodex;
  vector<string> names;
  names.push_back("George");
  names.push_back("John");
  names.push_back("Thomas");
  EXPECT_CALL(rolodex, GetNames(_))
      .WillOnce(SetArrayArgument<0>(names.begin(), names.end()));
```

## Changing a Mock Object's Behavior Based on the State ##

If you expect a call to change the behavior of a mock object, you can use `::testing::InSequence` to specify different behaviors before and after the call:

```
using ::testing::InSequence;
using ::testing::Return;

...
  {
    InSequence seq;
    EXPECT_CALL(my_mock, IsDirty())
        .WillRepeatedly(Return(true));
    EXPECT_CALL(my_mock, Flush());
    EXPECT_CALL(my_mock, IsDirty())
        .WillRepeatedly(Return(false));
  }
  my_mock.FlushIfDirty();
```

This makes `my_mock.IsDirty()` return `true` before `my_mock.Flush()` is called and return `false` afterwards.

If the behavior change is more complex, you can store the effects in a variable and make a mock method get its return value from that variable:

```
using ::testing::_;
using ::testing::SaveArg;
using ::testing::Return;

ACTION_P(ReturnPointee, p) { return *p; }
...
  int previous_value = 0;
  EXPECT_CALL(my_mock, GetPrevValue())
      .WillRepeatedly(ReturnPointee(&previous_value));
  EXPECT_CALL(my_mock, UpdateValue(_))
      .WillRepeatedly(SaveArg<0>(&previous_value));
  my_mock.DoSomethingToUpdateValue();
```

Here `my_mock.GetPrevValue()` will always return the argument of the last `UpdateValue()` call.

## Setting the Default Value for a Return Type ##

If a mock method's return type is a built-in C++ type or pointer, by
default it will return 0 when invoked. You only need to specify an
action if this default value doesn't work for you.

Sometimes, you may want to change this default value, or you may want
to specify a default value for types Google Mock doesn't know
about. You can do this using the `::testing::DefaultValue` class
template:

```
class MockFoo : public Foo {
 public:
  MOCK_METHOD0(CalculateBar, Bar());
};
...

  Bar default_bar;
  // Sets the default return value for type Bar.
  DefaultValue<Bar>::Set(default_bar);

  MockFoo foo;

  // We don't need to specify an action here, as the default
  // return value works for us.
  EXPECT_CALL(foo, CalculateBar());

  foo.CalculateBar();  // This should return default_bar.

  // Unsets the default return value.
  DefaultValue<Bar>::Clear();
```

Please note that changing the default value for a type can make you
tests hard to understand. We recommend you to use this feature
judiciously. For example, you may want to make sure the `Set()` and
`Clear()` calls are right next to the code that uses your mock.

## Setting the Default Actions for a Mock Method ##

You've learned how to change the default value of a given
type. However, this may be too coarse for your purpose: perhaps you
have two mock methods with the same return type and you want them to
have different behaviors. The `ON_CALL()` macro allows you to
customize your mock's behavior at the method level:

```
using ::testing::_;
using ::testing::AnyNumber;
using ::testing::Gt;
using ::testing::Return;
...
  ON_CALL(foo, Sign(_))
      .WillByDefault(Return(-1));
  ON_CALL(foo, Sign(0))
      .WillByDefault(Return(0));
  ON_CALL(foo, Sign(Gt(0)))
      .WillByDefault(Return(1));

  EXPECT_CALL(foo, Sign(_))
      .Times(AnyNumber());

  foo.Sign(5);   // This should return 1.
  foo.Sign(-9);  // This should return -1.
  foo.Sign(0);   // This should return 0.
```

As you may have guessed, when there are more than one `ON_CALL()`
statements, the news order take precedence over the older ones. In
other words, the **last** one that matches the function arguments will
be used. This matching order allows you to set up the common behavior
in a mock object's constructor or the test fixture's set-up phase and
specialize the mock's behavior later.

## Using Functions/Methods/Functors as Actions ##

If the built-in actions don't suit you, you can easily use an existing
function, method, or functor as an action:

```
using ::testing::_;
using ::testing::Invoke;

class MockFoo : public Foo {
 public:
  MOCK_METHOD2(Sum, int(int x, int y));
  MOCK_METHOD1(ComplexJob, bool(int x));
};

int CalculateSum(int x, int y) { return x + y; }

class Helper {
 public:
  bool ComplexJob(int x);
};
...

  MockFoo foo;
  Helper helper;
  EXPECT_CALL(foo, Sum(_, _))
      .WillOnce(Invoke(CalculateSum));
  EXPECT_CALL(foo, ComplexJob(_))
      .WillOnce(Invoke(&helper, &Helper::ComplexJob));

  foo.Sum(5, 6);       // Invokes CalculateSum(5, 6).
  foo.ComplexJob(10);  // Invokes helper.ComplexJob(10);
```

The only requirement is that the type of the function, etc must be
_compatible_ with the signature of the mock function, meaning that the
latter's arguments can be implicitly converted to the corresponding
arguments of the former, and the former's return type can be
implicitly converted to that of the latter. So, you can invoke
something whose type is _not_ exactly the same as the mock function,
as long as it's safe to do so - nice, huh?

## Invoking a Function/Method/Functor Without Arguments ##

`Invoke()` is very useful for doing actions that are more complex. It
passes the mock function's arguments to the function or functor being
invoked such that the callee has the full context of the call to work
with. If the invoked function is not interested in some or all of the
arguments, it can simply ignore them.

Yet, a common pattern is that a test author wants to invoke a function
without the arguments of the mock function. `Invoke()` allows her to
do that using a wrapper function that throws away the arguments before
invoking an underlining nullary function. Needless to say, this can be
tedious and obscures the intent of the test.

`InvokeWithoutArgs()` solves this problem. It's like `Invoke()` except
that it doesn't pass the mock function's arguments to the
callee. Here's an example:

```
using ::testing::_;
using ::testing::InvokeWithoutArgs;

class MockFoo : public Foo {
 public:
  MOCK_METHOD1(ComplexJob, bool(int n));
};

bool Job1() { ... }
...

  MockFoo foo;
  EXPECT_CALL(foo, ComplexJob(_))
      .WillOnce(InvokeWithoutArgs(Job1));

  foo.ComplexJob(10);  // Invokes Job1().
```

## Invoking an Argument of the Mock Function ##

Sometimes a mock function will receive a function pointer or a functor
(in other words, a "callable") as an argument, e.g.

```
class MockFoo : public Foo {
 public:
  MOCK_METHOD2(DoThis, bool(int n, bool (*fp)(int)));
};
```

and you may want to invoke this callable argument:

```
using ::testing::_;
...
  MockFoo foo;
  EXPECT_CALL(foo, DoThis(_, _))
      .WillOnce(...);
  // Will execute (*fp)(5), where fp is the
  // second argument DoThis() receives.
```

Arghh, you need to refer to a mock function argument but C++ has no
lambda (yet), so you have to define your own action. :-( Or do you
really?

Well, Google Mock has an action to solve _exactly_ this problem:

```
  InvokeArgument<N>(arg_1, arg_2, ..., arg_m)
```

will invoke the `N`-th (0-based) argument the mock function receives,
with `arg_1`, `arg_2`, ..., and `arg_m`. No matter if the argument is
a function pointer or a functor, Google Mock handles them both.

With that, you could write:

```
using ::testing::_;
using ::testing::InvokeArgument;
...
  EXPECT_CALL(foo, DoThis(_, _))
      .WillOnce(InvokeArgument<1>(5));
  // Will execute (*fp)(5), where fp is the
  // second argument DoThis() receives.
```

What if the callable takes an argument by reference? No problem - just
wrap it inside `ByRef()`:

```
...
  MOCK_METHOD1(Bar, bool(bool (*fp)(int, const Helper&)));
...
using ::testing::_;
using ::testing::ByRef;
using ::testing::InvokeArgument;
...

  MockFoo foo;
  Helper helper;
  ...
  EXPECT_CALL(foo, Bar(_))
      .WillOnce(InvokeArgument<0>(5, ByRef(helper)));
  // ByRef(helper) guarantees that a reference to helper, not a copy of it,
  // will be passed to the callable.
```

What if the callable takes an argument by reference and we do **not**
wrap the argument in `ByRef()`? Then `InvokeArgument()` will _make a
copy_ of the argument, and pass a _reference to the copy_, instead of
a reference to the original value, to the callable. This is especially
handy when the argument is a temporary value:

```
...
  MOCK_METHOD1(DoThat, bool(bool (*f)(const double& x, const string& s)));
...
using ::testing::_;
using ::testing::InvokeArgument;
...

  MockFoo foo;
  ...
  EXPECT_CALL(foo, DoThat(_))
      .WillOnce(InvokeArgument<0>(5.0, string("Hi")));
  // Will execute (*f)(5.0, string("Hi")), where f is the function pointer
  // DoThat() receives.  Note that the values 5.0 and string("Hi") are
  // temporary and dead once the EXPECT_CALL() statement finishes.  Yet
  // it's fine to perform this action later, since a copy of the values
  // are kept inside the InvokeArgument action.
```

## Ignoring an Action's Result ##

Sometimes you have an action that returns _something_, but you need an
action that returns `void` (perhaps you want to use it in a mock
function that returns `void`, or perhaps it needs to be used in
`DoAll()` and it's not the last in the list). `IgnoreResult()` lets
you do that. For example:

```
using ::testing::_;
using ::testing::Invoke;
using ::testing::Return;

int Process(const MyData& data);
string DoSomething();

class MockFoo : public Foo {
 public:
  MOCK_METHOD1(Abc, void(const MyData& data));
  MOCK_METHOD0(Xyz, bool());
};
...

  MockFoo foo;
  EXPECT_CALL(foo, Abc(_))
  // .WillOnce(Invoke(Process));
  // The above line won't compile as Process() returns int but Abc() needs
  // to return void.
      .WillOnce(IgnoreResult(Invoke(Process)));

  EXPECT_CALL(foo, Xyz())
      .WillOnce(DoAll(IgnoreResult(Invoke(DoSomething)),
      // Ignores the string DoSomething() returns.
                      Return(true)));
```

Note that you **cannot** use `IgnoreResult()` on an action that already
returns `void`. Doing so will lead to ugly compiler errors.

## Selecting an Action's Arguments ##

Say you have a mock function `Foo()` that takes seven arguments, and
you have a custom action that you want to invoke when `Foo()` is
called. Trouble is, the custom action only wants three arguments:

```
using ::testing::_;
using ::testing::Invoke;
...
  MOCK_METHOD7(Foo, bool(bool visible, const string& name, int x, int y,
                         const map<pair<int, int>, double>& weight,
                         double min_weight, double max_wight));
...

bool IsVisibleInQuadrant1(bool visible, int x, int y) {
  return visible && x >= 0 && y >= 0;
}
...

  EXPECT_CALL(mock, Foo(_, _, _, _, _, _, _))
      .WillOnce(Invoke(IsVisibleInQuadrant1));  // Uh, won't compile. :-(
```

To please the compiler God, you can to define an "adaptor" that has
the same signature as `Foo()` and calls the custom action with the
right arguments:

```
using ::testing::_;
using ::testing::Invoke;

bool MyIsVisibleInQuadrant1(bool visible, const string& name, int x, int y,
                            const map<pair<int, int>, double>& weight,
                            double min_weight, double max_wight) {
  return IsVisibleInQuadrant1(visible, x, y);
}
...

  EXPECT_CALL(mock, Foo(_, _, _, _, _, _, _))
      .WillOnce(Invoke(MyIsVisibleInQuadrant1));  // Now it works.
```

But isn't this awkward?

Google Mock provides a generic _action adaptor_, so you can spend your
time minding more important business than writing your own
adaptors. Here's the syntax:

```
  WithArgs<N1, N2, ..., Nk>(action)
```

creates an action that passes the arguments of the mock function at
the given indices (0-based) to the inner `action` and performs
it. Using `WithArgs`, our original example can be written as:

```
using ::testing::_;
using ::testing::Invoke;
using ::testing::WithArgs;
...
  EXPECT_CALL(mock, Foo(_, _, _, _, _, _, _))
      .WillOnce(WithArgs<0, 2, 3>(Invoke(IsVisibleInQuadrant1)));
      // No need to define your own adaptor.
```

For better readability, Google Mock also gives you:

  * `WithoutArgs(action)` when the inner `action` takes _no_ argument, and
  * `WithArg<N>(action)` (no `s` after `Arg`) when the inner `action` takes _one_ argument.

As you may have realized, `InvokeWithoutArgs(...)` is just syntactic
sugar for `WithoutArgs(Inovke(...))`.

Here are more tips:

  * The inner action used in `WithArgs` and friends does not have to be `Invoke()` -- it can be anything.
  * You can repeat an argument in the argument list if necessary, e.g. `WithArgs<2, 3, 3, 5>(...)`.
  * You can change the order of the arguments, e.g. `WithArgs<3, 2, 1>(...)`.
  * The types of the selected arguments do _not_ have to match the signature of the inner action exactly. It works as long as they can be implicitly converted to the corresponding arguments of the inner action. For example, if the 4-th argument of the mock function is an `int` and `my_action` takes a `double`, `WithArg<4>(my_action)` will work.

## Ignoring Arguments in Action Functions ##

The selecting-an-action's-arguments recipe showed us one way to make a
mock function and an action with incompatible argument lists fit
together. The downside is that wrapping the action in
`WithArgs<...>()` can get tedious for people writing the tests.

If you are defining a function, method, or functor to be used with
`Invoke*()`, and you are not interested in some of its arguments, an
alternative to `WithArgs` is to declare the uninteresting arguments as
`Unused`. This makes the definition less cluttered and less fragile in
case the types of the uninteresting arguments change. It could also
increase the chance the action function can be reused. For example,
given

```
  MOCK_METHOD3(Foo, double(const string& label, double x, double y));
  MOCK_METHOD3(Bar, double(int index, double x, double y));
```

instead of

```
using ::testing::_;
using ::testing::Invoke;

double DistanceToOriginWithLabel(const string& label, double x, double y) {
  return sqrt(x*x + y*y);
}

double DistanceToOriginWithIndex(int index, double x, double y) {
  return sqrt(x*x + y*y);
}
...

  EXEPCT_CALL(mock, Foo("abc", _, _))
      .WillOnce(Invoke(DistanceToOriginWithLabel));
  EXEPCT_CALL(mock, Bar(5, _, _))
      .WillOnce(Invoke(DistanceToOriginWithIndex));
```

you could write

```
using ::testing::_;
using ::testing::Invoke;
using ::testing::Unused;

double DistanceToOrigin(Unused, double x, double y) {
  return sqrt(x*x + y*y);
}
...

  EXEPCT_CALL(mock, Foo("abc", _, _))
      .WillOnce(Invoke(DistanceToOrigin));
  EXEPCT_CALL(mock, Bar(5, _, _))
      .WillOnce(Invoke(DistanceToOrigin));
```

## Sharing Actions ##

Just like matchers, a Google Mock action object consists of a pointer
to a ref-counted implementation object. Therefore copying actions is
also allowed and very efficient. When the last action that references
the implementation object dies, the implementation object will be
deleted.

If you have some complex action that you want to use again and again,
you may not have to build it from scratch everytime. If the action
doesn't have an internal state (i.e. if it always does the same thing
no matter how many times it has been called), you can assign it to an
action variable and use that variable repeatedly. For example:

```
  Action<bool(int*)> set_flag = DoAll(SetArgPointee<0>(5),
                                      Return(true));
  ... use set_flag in .WillOnce() and .WillRepeatedly() ...
```

However, if the action has its own state, you may be surprised if you
share the action object. Suppose you have an action factory
`IncrementCounter(init)` which creates an action that increments and
returns a counter whose initial value is `init`, using two actions
created from the same expression and using a shared action will
exihibit different behaviors. Example:

```
  EXPECT_CALL(foo, DoThis())
      .WillRepeatedly(IncrementCounter(0));
  EXPECT_CALL(foo, DoThat())
      .WillRepeatedly(IncrementCounter(0));
  foo.DoThis();  // Returns 1.
  foo.DoThis();  // Returns 2.
  foo.DoThat();  // Returns 1 - Blah() uses a different
                 // counter than Bar()'s.
```

versus

```
  Action<int()> increment = IncrementCounter(0);

  EXPECT_CALL(foo, DoThis())
      .WillRepeatedly(increment);
  EXPECT_CALL(foo, DoThat())
      .WillRepeatedly(increment);
  foo.DoThis();  // Returns 1.
  foo.DoThis();  // Returns 2.
  foo.DoThat();  // Returns 3 - the counter is shared.
```

# Misc Recipes on Using Google Mock #

## Making the Compilation Faster ##

Believe it or not, the _vast majority_ of the time spent on compiling
a mock class is in generating its constructor and destructor, as they
perform non-trivial tasks (e.g. verification of the
expectations). What's more, mock methods with different signatures
have different types and thus their constructors/destructors need to
be generated by the compiler separately. As a result, if you mock many
different types of methods, compiling your mock class can get really
slow.

If you are experiencing slow compilation, you can move the definition
of your mock class' constructor and destructor out of the class body
and into a `.cpp` file. This way, even if you `#include` your mock
class in N files, the compiler only needs to generate its constructor
and destructor once, resulting in a much faster compilation.

Let's illustrate the idea using an example. Here's the definition of a
mock class before applying this recipe:

```
// File mock_foo.h.
...
class MockFoo : public Foo {
 public:
  // Since we don't declare the constructor or the destructor,
  // the compiler will generate them in every translation unit
  // where this mock class is used.

  MOCK_METHOD0(DoThis, int());
  MOCK_METHOD1(DoThat, bool(const char* str));
  ... more mock methods ...
};
```

After the change, it would look like:

```
// File mock_foo.h.
...
class MockFoo : public Foo {
 public:
  // The constructor and destructor are declared, but not defined, here.
  MockFoo();
  virtual ~MockFoo();

  MOCK_METHOD0(DoThis, int());
  MOCK_METHOD1(DoThat, bool(const char* str));
  ... more mock methods ...
};
```
and
```
// File mock_foo.cpp.
#include "path/to/mock_foo.h"

// The definitions may appear trivial, but the functions actually do a
// lot of things through the constructors/destructors of the member
// variables used to implement the mock methods.
MockFoo::MockFoo() {}
MockFoo::~MockFoo() {}
```

## Forcing a Verification ##

When it's being destoyed, your friendly mock object will automatically
verify that all expectations on it have been satisfied, and will
generate [Google Test](http://code.google.com/p/googletest/) failures
if not. This is convenient as it leaves you with one less thing to
worry about. That is, unless you are not sure if your mock object will
be destoyed.

How could it be that your mock object won't eventually be destroyed?
Well, it might be created on the heap and owned by the code you are
testing. Suppose there's a bug in that code and it doesn't delete the
mock object properly - you could end up with a passing test when
there's actually a bug.

Using a heap checker is a good idea and can alleviate the concern, but
its implementation may not be 100% reliable. So, sometimes you do want
to _force_ Google Mock to verify a mock object before it is
(hopefully) destructed. You can do this with
`Mock::VerifyAndClearExpectations(&mock_object)`:

```
TEST(MyServerTest, ProcessesRequest) {
  using ::testing::Mock;

  MockFoo* const foo = new MockFoo;
  EXPECT_CALL(*foo, ...)...;
  // ... other expectations ...

  // server now owns foo.
  MyServer server(foo);
  server.ProcessRequest(...);

  // In case that server's destructor will forget to delete foo,
  // this will verify the expectations anyway.
  Mock::VerifyAndClearExpectations(foo);
}  // server is destroyed when it goes out of scope here.
```

**Tip:** The `Mock::VerifyAndClearExpectations()` function returns a
`bool` to indicate whether the verification was successful (`true` for
yes), so you can wrap that function call inside a `ASSERT_TRUE()` if
there is no point going further when the verification has failed.

## Using Check Points ##

Sometimes you may want to "reset" a mock object at various check
points in your test: at each check point, you verify that all existing
expectations on the mock object have been satisfied, and then you set
some new expectations on it as if it's newly created. This allows you
to work with a mock object in "phases" whose sizes are each
manageable.

One such scenario is that in your test's `SetUp()` function, you may
want to put the object you are testing into a certain state, with the
help from a mock object. Once in the desired state, you want to clear
all expectations on the mock, such that in the `TEST_F` body you can
set fresh expectations on it.

As you may have figured out, the `Mock::VerifyAndClearExpectations()`
function we saw in the previous recipe can help you here. Or, if you
are using `ON_CALL()` to set default actions on the mock object and
want to clear the default actions as well, use
`Mock::VerifyAndClear(&mock_object)` instead. This function does what
`Mock::VerifyAndClearExpectations(&mock_object)` does and returns the
same `bool`, **plus** it clears the `ON_CALL()` statements on
`mock_object` too.

Another trick you can use to achieve the same effect is to put the
expectations in sequences and insert calls to a dummy "check-point"
function at specific places. Then you can verify that the mock
function calls do happen at the right time. For example, if you are
exercising code:

```
Foo(1);
Foo(2);
Foo(3);
```

and want to verify that `Foo(1)` and `Foo(3)` both invoke
`mock.Bar("a")`, but `Foo(2)` doesn't invoke anything. You can write:

```
using ::testing::MockFunction;

TEST(FooTest, InvokesBarCorrectly) {
  MyMock mock;
  // Class MockFunction<F> has exactly one mock method.  It is named
  // Call() and has type F.
  MockFunction<void(string check_point_name)> check;
  {
    InSequence s;

    EXPECT_CALL(mock, Bar("a"));
    EXPECT_CALL(check, Call("1"));
    EXPECT_CALL(check, Call("2"));
    EXPECT_CALL(mock, Bar("a"));
  }
  Foo(1);
  check.Call("1");
  Foo(2);
  check.Call("2");
  Foo(3);
}
```

The expectation spec says that the first `Bar("a")` must happen before
check point "1", the second `Bar("a")` must happen after check point "2",
and nothing should happen between the two check points. The explicit
check points make it easy to tell which `Bar("a")` is called by which
call to `Foo()`.

## Mocking Destructors ##

Sometimes you want to make sure a mock object is destructed at the