Fixed #15838 -- Promoted assertFieldOutput to a general test utility. Thanks to Ramiro Morales for the patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16653 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/topics/testing.txt

@@ -1178,6 +1178,7 @@ basic functionality like:
 
  * Saving and restoring the Python warning machinery state.
  * Checking that a callable :meth:`raises a certain exeception <TestCase.assertRaisesMessage>`.
+ * :meth:`Testing form field rendering <assertFieldOutput>`.
 
 If you need any of the other more complex and heavyweight Django-specific
 features like:
@@ -1523,6 +1524,26 @@ your test suite.
     failure. Similar to unittest's ``assertRaisesRegexp`` with the difference
     that ``expected_message`` isn't a regular expression.
 
+.. method:: assertFieldOutput(self, fieldclass, valid, invalid, field_args=None, field_kwargs=None, empty_value=u'')
+
+    Asserts that a form field behaves correctly with various inputs.
+
+    :param fieldclass: the class of the field to be tested.
+    :param valid: a dictionary mapping valid inputs to their expected cleaned
+        values.
+    :param invalid: a dictionary mapping invalid inputs to one or more raised
+        error messages.
+    :param field_args: the args passed to instantiate the field.
+    :param field_kwargs: the kwargs passed to instantiate the field.
+    :param empty_value: the expected clean output for inputs in ``EMPTY_VALUES``.
+
+    For example, the following code tests that an ``EmailField`` accepts
+    "a@a.com" as a valid email address, but rejects "aaa" with a reasonable
+    error message::
+
+        self.assertFieldOutput(EmailField, {'a@a.com': 'a@a.com'}, {'aaa': [u'Enter a valid e-mail address.']})
+
+
 .. method:: TestCase.assertContains(response, text, count=None, status_code=200, msg_prefix='')
 
     Asserts that a ``Response`` instance produced the given ``status_code`` and