ifneq ($(findstring MKL26Z64, $(MCU)),)
  # Cortex version
  MCU = cortex-m0plus

  # ARM version, CORTEX-M0/M1 are 6, CORTEX-M3/M4/M7 are 7
  ARMV = 6

  ## chip/board settings
  # - the next two should match the directories in
  #   <chibios>/os/hal/ports/$(MCU_FAMILY)/$(MCU_SERIES)
  MCU_FAMILY = KINETIS
  MCU_SERIES = KL2x

  # Linker script to use
  # - it should exist either in <chibios>/os/common/ports/ARMCMx/compilers/GCC/ld/
  #   or <keyboard_dir>/ld/
  # - NOTE: a custom ld script is needed for EEPROM on Teensy LC
  MCU_LDSCRIPT ?= MKL26Z64

  # Startup code to use
  #  - it should exist in <chibios>/os/common/ports/ARMCMx/compilers/GCC/mk/
  MCU_STARTUP ?= kl2x

  # Board: it should exist either in <chibios>/os/hal/boards/,
  # <keyboard_dir>/boards/, or drivers/boards/
  BOARD ?= PJRC_TEENSY_LC
endif

ifneq ($(findstring MK20DX128, $(MCU)),)
  # Cortex version
  MCU = cortex-m4

  # ARM version, CORTEX-M0/M1 are 6, CORTEX-M3/M4/M7 are 7
  ARMV = 7

  ## chip/board settings
  # - the next two should match the directories in
  #   <chibios>/os/hal/ports/$(MCU_FAMILY)/$(MCU_SERIES)
  MCU_FAMILY = KINETIS
  MCU_SERIES = K20x

  # Linker script to use
  # - it should exist either in <chibios>/os/common/ports/ARMCMx/compilers/GCC/ld/
  #   or <keyboard_dir>/ld/
  MCU_LDSCRIPT ?= MK20DX128

  # Startup code to use
  #  - it should exist in <chibios>/os/common/ports/ARMCMx/compilers/GCC/mk/
  MCU_STARTUP ?= k20x5

  # Board: it should exist either in <chibios>/os/hal/boards/,
  # <keyboard_dir>/boards/, or drivers/boards/
  BOARD ?= PJRC_TEENSY_3
endif

ifneq ($(findstring MK20DX256, $(MCU)),)
  # Cortex version
  MCU = cortex-m4

  # ARM version, CORTEX-M0/M1 are 6, CORTEX-M3/M4/M7 are 7
  ARMV = 7

  ## chip/board settings
  # - the next two should match the directories in
  #   <chibios>/os/hal/ports/$(MCU_FAMILY)/$(MCU_SERIES)
  MCU_FAMILY = KINETIS
  MCU_SERIES = K20x

  # Linker script to use
  # - it should exist either in <chibios>/os/common/ports/ARMCMx/compilers/GCC/ld/
  #   or <keyboard_dir>/ld/
  MCU_LDSCRIPT ?= MK20DX256

  # Startup code to use
  #  - it should exist in <chibios>/os/common/ports/ARMCMx/compilers/GCC/mk/
  MCU_STARTUP ?= k20x7

  # Board: it should exist either in <chibios>/os/hal/boards/,
  # <keyboard_dir>/boards/, or drivers/boards/
  BOARD ?= PJRC_TEENSY_3_1
endif

ifneq ($(findstring STM32F303, $(MCU)),)
  # Cortex version
  MCU = cortex-m4

  # ARM version, CORTEX-M0/M1 are 6, CORTEX-M3/M4/M7 are 7
  ARMV = 7

  ## chip/board settings
  # - the next two should match the directories in
  #   <chibios>/os/hal/ports/$(MCU_FAMILY)/$(MCU_SERIES)
  MCU_FAMILY = STM32
  MCU_SERIES = STM32F3xx

  # Linker script to use
  # - it should exist either in <chibios>/os/common/ports/ARMCMx/compilers/GCC/ld/
  #   or <keyboard_dir>/ld/
  MCU_LDSCRIPT ?= STM32F303xC

  # Startup code to use
  #  - it should exist in <chibios>/os/common/startup/ARMCMx/compilers/GCC/mk/
  MCU_STARTUP ?= stm32f3xx

  # Board: it should exist either in <chibios>/os/hal/boards/,
  # <keyboard_dir>/boards/, or drivers/boards/
  BOARD ?= GENERIC_STM32_F303XC

  USE_FPU ?= yes

  # Options to pass to dfu-util when flashing
  DFU_ARGS ?= -d 0483:df11 -a 0 -s 0x08000000:leave
  DFU_SUFFIX_ARGS ?= -v 0483 -p df11
endif

ifneq ($(findstring STM32F072, $(MCU)),)
  # Cortex version
  MCU = cortex-m0

  # ARM version, CORTEX-M0/M1 are 6, CORTEX-M3/M4/M7 are 7
  ARMV = 6

  ## chip/board settings
  # - the next two should match the directories in
  #   <chibios>/os/hal/ports/$(MCU_FAMILY)/$(MCU_SERIES)
  MCU_FAMILY = STM32
  MCU_SERIES = STM32F0xx

  # Linker script to use
  # - it should exist either in <chibios>/os/common/ports/ARMCMx/compilers/GCC/ld/
  #   or <keyboard_dir>/ld/
  MCU_LDSCRIPT ?= STM32F072xB

  # Startup code to use
  #  - it should exist in <chibios>/os/common/startup/ARMCMx/compilers/GCC/mk/
  MCU_STARTUP ?= stm32f0xx

  # Board: it should exist either in <chibios>/os/hal/boards/,
  # <keyboard_dir>/boards/, or drivers/boards/
  BOARD ?= GENERIC_STM32_F072XB

  USE_FPU ?= no

  # Options to pass to dfu-util when flashing
  DFU_ARGS ?= -d 0483:df11 -a 0 -s 0x08000000:leave
  DFU_SUFFIX_ARGS ?= -v 0483 -p df11
endif

ifneq ($(findstring STM32F042, $(MCU)),)
  # Cortex version
  MCU = cortex-m0

  # ARM version, CORTEX-M0/M1 are 6, CORTEX-M3/M4/M7 are 7
  ARMV = 6

  ## chip/board settings
  # - the next two should match the directories in
  #   <chibios>/os/hal/ports/$(MCU_FAMILY)/$(MCU_SERIES)
  MCU_FAMILY = STM32
  MCU_SERIES = STM32F0xx

  # Linker script to use
  # - it should exist either in <chibios>/os/common/ports/ARMCMx/compilers/GCC/ld/
  #   or <keyboard_dir>/ld/
  MCU_LDSCRIPT ?= STM32F042x6

  # Startup code to use
  #  - it should exist in <chibios>/os/common/startup/ARMCMx/compilers/GCC/mk/
  MCU_STARTUP ?= stm32f0xx

  # Board: it should exist either in <chibios>/os/hal/boards/,
  # <keyboard_dir>/boards/, or drivers/boards/
  BOARD ?= GENERIC_STM32_F042X6

  USE_FPU ?= no

  # Options to pass to dfu-util when flashing
  DFU_ARGS ?= -d 0483:df11 -a 0 -s 0x08000000:leave
  DFU_SUFFIX_ARGS ?= -v 0483 -p df11
endif

ifneq ($(findstring STM32F103, $(MCU)),)
  # Cortex version
  MCU = cortex-m3

  # ARM version, CORTEX-M0/M1 are 6, CORTEX-M3/M4/M7 are 7
  ARMV = 7

  ## chip/board settings
  # - the next two should match the directories in
  #   <chibios>/os/hal/ports/$(MCU_FAMILY)/$(MCU_SERIES)
  MCU_FAMILY = STM32
  MCU_SERIES = STM32F1xx

  # Linker script to use
  # - it should exist either in <chibios>/os/common/ports/ARMCMx/compilers/GCC/ld/
  #   or <keyboard_dir>/ld/
  MCU_LDSCRIPT ?= STM32F103x8

  # Startup code to use
  #  - it should exist in <chibios>/os/common/startup/ARMCMx/compilers/GCC/mk/
  MCU_STARTUP ?= stm32f1xx

  # Board: it should exist either in <chibios>/os/hal/boards/,
  # <keyboard_dir>/boards/, or drivers/boards/
  BOARD ?= GENERIC_STM32_F103

  USE_FPU ?= no

  # Options to pass to dfu-util when flashing
  DFU_ARGS ?= -d 0483:df11 -a 0 -s 0x08000000:leave
  DFU_SUFFIX_ARGS ?= -v 0483 -p df11
endif

ifneq (,$(filter $(MCU),atmega16u2 atmega32u2 atmega16u4 atmega32u4 at90usb646 at90usb1286))
  PROTOCOL = LUFA

  # Processor frequency.
  #     This will define a symbol, F_CPU, in all source code files equal to the
  #     processor frequency in Hz. You can then use this symbol in your source code to
  #     calculate timings. Do NOT tack on a 'UL' at the end, this will be done
  #     automatically to create a 32-bit value in your source code.
  #
  #     This will be an integer division of F_USB below, as it is sourced by
  #     F_USB after it has run through any CPU prescalers. Note that this value
  #     does not *change* the processor frequency - it should merely be updated to
  #     reflect the processor speed set externally so that the code can use accurate
  #     software delays.
  F_CPU ?= 16000000

  # LUFA specific
  #
  # Target architecture (see library "Board Types" documentation).
  ARCH = AVR8

  # Input clock frequency.
  #     This will define a symbol, F_USB, in all source code files equal to the
  #     input clock frequency (before any prescaling is performed) in Hz. This value may
  #     differ from F_CPU if prescaling is used on the latter, and is required as the
  #     raw input clock is fed directly to the PLL sections of the AVR for high speed
  #     clock generation for the USB and other AVR subsections. Do NOT tack on a 'UL'
  #     at the end, this will be done automatically to create a 32-bit value in your
  #     source code.
  #
  #     If no clock division is performed on the input clock inside the AVR (via the
  #     CPU clock adjust registers or the clock division fuses), this will be equal to F_CPU.
  F_USB ?= $(F_CPU)

  # Interrupt driven control endpoint task
  ifeq (,$(filter $(NO_INTERRUPT_CONTROL_ENDPOINT),yes))
    OPT_DEFS += -DINTERRUPT_CONTROL_ENDPOINT
  endif
endif

ifneq (,$(filter $(MCU),atmega32a))
  # MCU name for avrdude
  AVRDUDE_MCU = m32

  PROTOCOL = VUSB

  # Processor frequency.
  #     This will define a symbol, F_CPU, in all source code files equal to the
  #     processor frequency in Hz. You can then use this symbol in your source code to
  #     calculate timings. Do NOT tack on a 'UL' at the end, this will be done
  #     automatically to create a 32-bit value in your source code.
  F_CPU ?= 12000000

  # unsupported features for now
  NO_UART ?= yes
  NO_SUSPEND_POWER_DOWN ?= yes
endif

ifneq (,$(filter $(MCU),atmega328p))
  # MCU name for avrdude
  AVRDUDE_MCU = m328p

  PROTOCOL = VUSB

  # Processor frequency.
  #     This will define a symbol, F_CPU, in all source code files equal to the
  #     processor frequency in Hz. You can then use this symbol in your source code to
  #     calculate timings. Do NOT tack on a 'UL' at the end, this will be done
  #     automatically to create a 32-bit value in your source code.
  F_CPU ?= 16000000

  # unsupported features for now
  NO_UART ?= yes
  NO_SUSPEND_POWER_DOWN ?= yes
endif
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.highlight .il { color: #0000DD; font-weight: bold } /* Literal.Number.Integer.Long */</style><div class="highlight"><pre><span></span><span class="gh"># Unit Testing</span>

If you are new to unit testing, then you can find many good resources on internet. However most of it is scattered around in small pieces here and there, and there&#39;s also many different opinions, so I won&#39;t give any recommendations.

Instead I recommend these two books, explaining two different styles of Unit Testing in detail.

<span class="k">*</span> &quot;Test Driven Development: By Example: Kent Beck&quot;
<span class="k">*</span> &quot;Growing Object-Oriented Software, Guided By Tests: Steve Freeman, Nat Pryce&quot;

If you prefer videos there are Uncle Bob&#39;s [<span class="nt">Clean Coders Videos</span>](<span class="na">https://cleancoders.com/</span>), which unfortunately cost quite a bit, especially if you want to watch many of them. But James Shore has a free [<span class="nt">Let&#39;s Play</span>](<span class="na">http://www.jamesshore.com/Blog/Lets-Play</span>) video series.

<span class="gu">## Google Test and Google Mock</span>
It&#39;s possible to Unit Test your code using [<span class="nt">Google Test</span>](<span class="na">https://github.com/google/googletest</span>). The Google Test framework also includes another component for writing testing mocks and stubs, called &quot;Google Mock&quot;. For information how to write the actual tests, please refer to the documentation on that site.

<span class="gu">## Use of C++</span>

Note that Google Test and therefore any test has to be written in C++, even if the rest of the QMK codebases is written in C. This should hopefully not be a problem even if you don&#39;t know any C++, since there&#39;s quite clear documentation and examples of the required C++ features, and you can write the rest of the test code almost as you would write normal C. Note that some compiler errors which you might get can look quite scary, but just read carefully what it says, and you should be ok.

One thing to remember, is that you have to append <span class="sb">`extern &quot;C&quot;`</span> around all of your C file includes.

<span class="gu">## Adding tests for new or existing features</span>

If you want to unit test some feature, then take a look at the existing serial_link tests, in the <span class="sb">`quantum/serial_link/tests folder`</span>, and follow the steps below to create a similar structure.

<span class="k">1.</span> If it doesn&#39;t already exist, add a test subfolder to the folder containing the feature.
<span class="k">2.</span> Create a <span class="sb">`testlist.mk`</span> and a <span class="sb">`rules.mk`</span> file in that folder.
<span class="k">3.</span> Include those files from the root folder <span class="sb">`testlist.mk`</span>and <span class="sb">`build_test.mk`</span> respectively.
<span class="k">4.</span> Add a new name for your testgroup to the <span class="sb">`testlist.mk`</span> file. Each group defined there will be a separate executable. And that&#39;s how you can support mocking out different parts. Note that it&#39;s worth adding some common prefix, just like it&#39;s done for the serial_link tests. The reason for that is that the make command allows substring filtering, so this way you can easily run a subset of the tests.