Fixed #16 - Incorrect test duration with freezegun

freezegun is a Python library used to set the date/time returned by
the Python date/time functions to make testing time-sensitive code
easier.

time.time() is used here to measure the duration of test cases, if
freezegun was in use then the time returned by this could be the
time the test had set up, rather than the actual time. This lead to
test durations being reported as negative (if frozen time is in the
past), or much longer than expected (if fronzen time is in the
future).

freezegun exposes the unmodified time.time() via an alias. This
changes TimingSuite so that it uses this alias if freezegun is
installed.

.travis.yml

@@ -16,7 +16,7 @@ env:
     - DJANGO=Django==1.6.11
 
 install:
-  - pip install flake8 coverage coveralls $DJANGO
+  - pip install flake8 coverage coveralls $DJANGO freezegun
   - pip install -e .
 
 matrix:

django_slowtests/testrunner.py

@@ -7,6 +7,16 @@
 from django.conf import settings
 
 
+try:  # pragma: no cover
+    import freezegun
+
+    def _time():
+        return freezegun.api.real_time()
+except ImportError:  # pragma: no cover
+    def _time():
+        return time.time()
+
+
 TIMINGS = {}
 NUM_SLOW_TESTS = getattr(settings, 'NUM_SLOW_TESTS', 10)
 SLOW_TEST_THRESHOLD_MS = getattr(settings, 'SLOW_TEST_THRESHOLD_MS', 0)
@@ -26,7 +36,7 @@ def run(self, result, debug=False):
             if result.shouldStop:
                 break
 
-            start_time = time.time()
+            start_time = _time()
 
             if _isnotsuite(test):
                 self._tearDownPreviousClass(test, result)
@@ -43,7 +53,7 @@ def run(self, result, debug=False):
             else:
                 test.debug()
 
-            TIMINGS[str(test)] = time.time() - start_time
+            TIMINGS[str(test)] = _time() - start_time
 
         if topLevel:
             self._tearDownPreviousClass(None, result)

django_slowtests/tests/fake.py

@@ -1,5 +1,6 @@
 import time
 from django.test import TestCase
+from freezegun import freeze_time
 
 
 class FakeTestCase(TestCase):
@@ -15,3 +16,17 @@ def test_slow_thing(self):
 
     def test_setup_class_was_run(self):
         self.assertTrue(self._setupClassRan)
+
+
+@freeze_time('2016-02-03 12:34:56')
+class FakeFrozenInPastTestCase(TestCase):
+
+    def test_this_should_not_have_a_negative_duration(self):
+        self.assertTrue(True)
+
+
+@freeze_time('3017-02-03 12:34:56')
+class FakeFrozenInFutureTestCase(TestCase):
+
+    def test_this_should_not_have_very_long_duration(self):
+        self.assertTrue(True)

django_slowtests/tests/tests.py

@@ -1,10 +1,13 @@
 from django.test import TestCase
 from unittest import TestResult
-from ..testrunner import TimingSuite
+from ..testrunner import TimingSuite, TIMINGS
 
 
 class TimingSuiteTests(TestCase):
 
+    def setUp(self):
+        TIMINGS.clear()
+
     def test_add_a_test(self):
         from .fake import FakeTestCase
         suite = TimingSuite()
@@ -14,3 +17,23 @@ def test_add_a_test(self):
         suite.run(result)
         self.assertEquals(len(suite._tests), 2)
         self.assertEquals(len(result.errors), 0)
+
+    def test_timing_is_correct_when_freezegun_sets_time_in_past(self):
+        from .fake import FakeFrozenInPastTestCase
+        suite = TimingSuite()
+        result = TestResult()
+        suite.addTest(FakeFrozenInPastTestCase('test_this_should_not_have_a_negative_duration'))
+        suite.run(result)
+        test_name = str(suite._tests[0])
+        self.assertTrue(TIMINGS[test_name] > 0)
+        self.assertTrue(TIMINGS[test_name] < 1)
+
+    def test_timing_is_correct_when_freezegun_sets_time_in_future(self):
+        from .fake import FakeFrozenInFutureTestCase
+        suite = TimingSuite()
+        result = TestResult()
+        suite.addTest(FakeFrozenInFutureTestCase('test_this_should_not_have_very_long_duration'))
+        suite.run(result)
+        test_name = str(suite._tests[0])
+        self.assertTrue(TIMINGS[test_name] > 0)
+        self.assertTrue(TIMINGS[test_name] < 1)

tox.ini

@@ -9,4 +9,5 @@ deps =
     dj1.8: Django>=1.8,<1.9
     dj1.9: Django>=1.9,<1.10
     dj1.10: Django>=1.10,<1.11
+    freezegun>=0.1.8
 commands = coverage run setup.py test