whwkong · February 16, 2019 19:07 · Feb 16, 2019 · Feb 16, 2019 · Feb 16, 2019 · Feb 16, 2019
diff --git a/mixins_as_fixtures.py b/mixins_as_fixtures.py
@@ -37,7 +37,7 @@ def testSub1(self):
     https://python-history.blogspot.com/2010/06/method-resolution-order.html
 
 
-$ python fixture_test.py
+# Output
 SecondMixin setUp
 FirstMixin setUp
 RealTest setUp

diff --git a/mixins_as_fixtures.py b/mixins_as_fixtures.py
@@ -23,14 +23,20 @@ def testSub1(self):
 
 The problem is that a class that inherits from another TestCase will run all the tests
 of the parent class.
+
+However, if you just want to extract the setUp(), then move the common setup code into a
+mixin.  Make that your mixins do not have any tests.
+
+This pattern relies on each mixin's setUp() calling `super().setUp(), and that
+unittest.TestCase is the last parent class (TestCase does not invoke a call to super,
+as object.setUp() does not exist).
+
 See:
     https://stackoverflow.com/questions/1323455/python-unit-test-with-base-and-sub-class/17696807#17696807
     https://nedbatchelder.com/blog/201210/multiple_inheritance_is_hard.html
+    https://python-history.blogspot.com/2010/06/method-resolution-order.html
 
 
-However, if you just want to extract the setUp(), then move the common setup code into a
-mixin.  Make that your mixins do not have any tests.
-
 $ python fixture_test.py
 SecondMixin setUp
 FirstMixin setUp

diff --git a/mixins_as_fixtures.py b/mixins_as_fixtures.py
@@ -25,6 +25,7 @@ def testSub1(self):
 of the parent class.
 See:
     https://stackoverflow.com/questions/1323455/python-unit-test-with-base-and-sub-class/17696807#17696807
+    https://nedbatchelder.com/blog/201210/multiple_inheritance_is_hard.html
 
 
 However, if you just want to extract the setUp(), then move the common setup code into a

diff --git a/mixins_as_fixtures.py b/mixins_as_fixtures.py
@@ -1,5 +1,5 @@
 """
-Consider that you want to reuse the setUp() of a some base class that derives from
+Consider the case of reusing the setUp() of a some base class that derives from
 unittest.TestCase.
 
 class BaseTest(unittest.TestCase):
@@ -27,8 +27,8 @@ def testSub1(self):
     https://stackoverflow.com/questions/1323455/python-unit-test-with-base-and-sub-class/17696807#17696807
 
 
-However, if you just want to extract the setUp(), then move the common code into a
-mixture.
+However, if you just want to extract the setUp(), then move the common setup code into a
+mixin.  Make that your mixins do not have any tests.
 
 $ python fixture_test.py
 SecondMixin setUp

diff --git a/mixins_as_fixtures.py b/mixins_as_fixtures.py
@@ -29,6 +29,20 @@ def testSub1(self):
 
 However, if you just want to extract the setUp(), then move the common code into a
 mixture.
+
+$ python fixture_test.py
+SecondMixin setUp
+FirstMixin setUp
+RealTest setUp
+RealTest test_foo
+SecondMixin tearDown
+FirstMixin tearDown
+RealTest tearDown
+.
+----------------------------------------------------------------------
+Ran 1 test in 0.000s
+
+OK
 """
 import unittest
 

diff --git a/mixins_as_fixtures.py b/mixins_as_fixtures.py
@@ -0,0 +1,70 @@
+"""
+Consider that you want to reuse the setUp() of a some base class that derives from
+unittest.TestCase.
+
+class BaseTest(unittest.TestCase):
+    def setUp(self):
+        super().setUp()
+        print('BaseTest setUp')
+
+    def testCommon(self):
+        print('Calling BaseTest:testCommon')
+        self.assertTrue(True)
+
+
+class SubTest1(BaseTest):
+    def setUp(self):
+        super().setUp()
+        print('SubTest1 setUp')
+
+    def testSub1(self):
+        print('Calling SubTest1:testSub1')
+        self.assertTrue(True)
+
+The problem is that a class that inherits from another TestCase will run all the tests
+of the parent class.
+See:
+    https://stackoverflow.com/questions/1323455/python-unit-test-with-base-and-sub-class/17696807#17696807
+
+
+However, if you just want to extract the setUp(), then move the common code into a
+mixture.
+"""
+import unittest
+
+
+class FirstMixin():
+    def setUp(self):
+        super().setUp()
+        print('FirstMixin setUp')
+
+    def tearDown(self):
+        super().tearDown()
+        print('FirstMixin tearDown')
+
+
+class SecondMixin():
+    def setUp(self):
+        super().setUp()
+        print('SecondMixin setUp')
+
+    def tearDown(self):
+        super().tearDown()
+        print('SecondMixin tearDown')
+
+
+class RealTest(FirstMixin, SecondMixin, unittest.TestCase):
+    def setUp(self):
+        super().setUp()
+        print('RealTest setUp')
+
+    def tearDown(self):
+        super().tearDown()
+        print('RealTest tearDown')
+
+    def test_foo(self):
+        print('RealTest test_foo')
+
+
+if __name__ == '__main__':
+    unittest.main()
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