Merge lp:~jelmer/testtools/assertIsInstance-msg into lp:~testtools-committers/testtools/trunk

[Jelmer Vernooij]

Add an optional "msg" argument for overriding the message to TestCase.assertIsInstance, for compatibility with Python 2.7's TestCase.assertDictEqual.

[Robert Collins (lifeless)]

Please add changes like this to NEWS. Also I've simplified your test.

review: Approve

[Robert Collins (lifeless)]

(And ideally in MANUAL, but jml has that in flux just now).

=== modified file 'testtools/testcase.py'
--- testtools/testcase.py	2010-11-27 10:51:14 +0000
+++ testtools/testcase.py	2010-12-12 04:13:52 +0000
@@ -300,10 +300,11 @@
         self.assertTrue(
             needle not in haystack, '%r in %r' % (needle, haystack))
 
-    def assertIsInstance(self, obj, klass):
-        self.assertTrue(
-            isinstance(obj, klass),
-            '%r is not an instance of %s' % (obj, self._formatTypes(klass)))
+    def assertIsInstance(self, obj, klass, msg=None):
+        if msg is None:
+            msg = '%r is not an instance of %s' % (
+                obj, self._formatTypes(klass))
+        self.assertTrue(isinstance(obj, klass), msg)
 
     def assertRaises(self, excClass, callableObj, *args, **kwargs):
         """Fail unless an exception of class excClass is thrown

=== modified file 'testtools/tests/test_testtools.py'
--- testtools/tests/test_testtools.py	2010-11-11 09:46:18 +0000
+++ testtools/tests/test_testtools.py	2010-12-12 04:13:52 +0000
@@ -375,6 +375,16 @@
             '42 is not an instance of %s' % self._formatTypes([Foo, Bar]),
             self.assertIsInstance, 42, (Foo, Bar))
 
+    def test_assertIsInstance_overridden_message(self):
+        # assertIsInstance(obj, klass, msg) fails the test with the specified
+        # message when obj is not an instance of klass.
+
+        class Foo(object):
+            """Simple class for testing assertIsInstance."""
+
+        self.assertFails("Bericht",
+            self.assertIsInstance, 42, Foo, "Bericht")
+
     def test_assertIs(self):
         # assertIs asserts that an object is identical to another object.
         self.assertIs(None, None)