Replacing test_osrandom_engine_is_default. (#2905)

* Removing test_osrandom_engine_is_default.

test_osrandom_engine_is_default depends on having a valid
sys.executable. This attribute is not always set (see
https://docs.python.org/2/library/sys.html#sys.executable ) so, in some
environments, this test fails. I moved the functionality of the test
into the setup and teardown methods so the correct behavior is still
tested.

* Fixing some style issues.

* Removing an unnecessary newline.

* Putting back the test.

* Moving the assert from teardown to setup.

1 files changed, 12 insertions, 0 deletions

diff --git a/tests/hazmat/backends/test_openssl.py b/tests/hazmat/backends/test_openssl.py
index 52bee7b3..a24f8ecd 100644
--- a/tests/hazmat/backends/test_openssl.py
+++ b/tests/hazmat/backends/test_openssl.py
@@ -208,6 +208,16 @@ class TestOpenSSL(object):
 
 
 class TestOpenSSLRandomEngine(object):
+
+    def setup(self):
+        # The default RAND engine is global and shared between
+        # tests. We make sure that the default engine is osrandom
+        # before we start each test and restore the global state to
+        # that engine in teardown.
+        current_default = backend._lib.ENGINE_get_default_RAND()
+        name = backend._lib.ENGINE_get_name(current_default)
+        assert name == backend._binding._osrandom_engine_name
+
     def teardown_method(self, method):
         # we need to reset state to being default. backend is a shared global
         # for all these tests.
@@ -216,6 +226,8 @@ class TestOpenSSLRandomEngine(object):
         name = backend._lib.ENGINE_get_name(current_default)
         assert name == backend._binding._osrandom_engine_name
 
+    @pytest.mark.skipif(sys.executable is None,
+                        reason="No Python interpreter available.")
     def test_osrandom_engine_is_default(self, tmpdir):
         engine_printer = textwrap.dedent(
             """