Escape % character in the assertion message. closes #604

--HG--
branch : test_for_issue_604

testing/test_assertmessage.py

@@ -1,18 +0,0 @@
-
-def test_assert_message_fail():
-    '''
-    Check if custom message with % sign do not raise ValueError
-    Later test can be parametrized with other problematic chars
-    '''
-
-    MESSAGE = 'Message with %'
-       
-    try:
-        assert False, MESSAGE
-    except ValueError, ve:
-        assert False, 'ValueError was raised with the following message: ' \
-            + ve.message
-    except AssertionError, ae:
-        assert MESSAGE == ae.message, 'Assertion message: ' + ae.message \
-            + ' is different than expected: ' + MESSAGE
-   

testing/test_assertrewrite.py

@@ -172,6 +172,18 @@ class TestAssertionRewrite:
             "*assert 1 == 2*",
         ])
 
+    def test_assertion_message_escape(self, testdir):
+        testdir.makepyfile("""
+            def test_foo():
+                assert 1 == 2, 'To be escaped: %'
+        """)
+        result = testdir.runpytest()
+        assert result.ret == 1
+        result.stdout.fnmatch_lines([
+            "*AssertionError: To be escaped: %",
+            "*assert 1 == 2",
+        ])
+
     def test_boolop(self):
         def f():
             f = g = False