unit_tests/test_cases: add tests for {Function,Method}TestCase.__repr__

At present, if a mutable argument is changed during the execution of test
case, then any printing of the test case object which occurs after the
test has run will result in the argument being printed with a __repr__ of
it's *new* state (assuming that its __repr__ is state-dependant). This is
particularly confusing when debugging failing test cases because the
summary lines and the failure-detail lines will show *different* __repr__s
of the args, e.g.

  nose_weirdness.test_nose_is_weird(Foo(10), 0) ... FAIL

  ======================================================================
  FAIL: nose_weirdness.test_nose_is_weird(Foo(0), 0)
  ----------------------------------------------------------------------
  ...
  Ran 1 test in 0.001s

  FAILED (failures=1)

This issue will be solved in the next commit.

1 files changed, 40 insertions, 0 deletions

diff --git a/unit_tests/test_cases.py b/unit_tests/test_cases.py
index af399e5..fd5302d 100644
--- a/unit_tests/test_cases.py
+++ b/unit_tests/test_cases.py
@@ -115,6 +115,46 @@ class TestNoseCases(unittest.TestCase):
         f(res)
         assert res.errors
 
+    def test_FunctionTestCase_repr_is_consistent_with_mutable_args(self):
+        class Foo(object):
+            def __init__(self):
+                self.bar = 'unmodified'
+            def __repr__(self):
+                return "Foo(%s)" % self.bar
+
+        def test_foo(foo):
+            pass
+
+        foo = Foo()
+        case = nose.case.FunctionTestCase(test_foo, arg=(foo,))
+        case_repr_before = case.__repr__()
+        foo.bar = "snafu'd!"
+        case_repr_after = case.__repr__()
+        assert case_repr_before == case_repr_after, (
+            "Modifying a mutable object arg during test case changed the test "
+            "case's __repr__")
+
+    def test_MethodTestCase_repr_is_consistent_with_mutable_args(self):
+        class Foo(object):
+            def __init__(self):
+                self.bar = 'unmodified'
+            def __repr__(self):
+                return "Foo(%s)" % self.bar
+
+        class FooTester(object):
+            def test_foo(self, foo):
+                pass
+
+        foo = Foo()
+        case = nose.case.FunctionTestCase(
+            unbound_method(FooTester, FooTester.test_foo), arg=(foo,))
+        case_repr_before = case.__repr__()
+        foo.bar = "snafu'd!"
+        case_repr_after = case.__repr__()
+        assert case_repr_before == case_repr_after, (
+            "Modifying a mutable object arg during test case changed the test "
+            "case's __repr__")
+
 
 class TestNoseTestWrapper(unittest.TestCase):
     def test_case_fixtures_called(self):