Method assertRaises

Lib/test/test_optparse.py:80–134

Assert that the expected exception is raised when calling a function, and that the right error message is included with that exception. Arguments: func -- the function to call args -- positional arguments to `func` kwargs -- keyword arg

(self,
                     func,
                     args,
                     kwargs,
                     expected_exception,
                     expected_message)

        return (options, positional_args)

    def assertRaises(self,
                     func,
                     args,
                     kwargs,
                     expected_exception,
                     expected_message):
        """
        Assert that the expected exception is raised when calling a
        function, and that the right error message is included with
        that exception.

        Arguments:
          func -- the function to call
          args -- positional arguments to `func`
          kwargs -- keyword arguments to `func`
          expected_exception -- exception that should be raised
          expected_message -- expected exception message (or pattern
            if a compiled regex object)

        Returns the exception raised for further testing.
        """
        if args is None:
            args = ()
        if kwargs is None:
            kwargs = {}

        try:
            func(*args, **kwargs)
        except expected_exception as err:
            actual_message = str(err)
            if isinstance(expected_message, re.Pattern):
                self.assertTrue(expected_message.search(actual_message),
                             """\
expected exception message pattern:
/%s/
actual exception message:
'''%s'''
""" % (expected_message.pattern, actual_message))
            else:
                self.assertEqual(actual_message,
                                 expected_message,
                                 """\
expected exception message:
'''%s'''
actual exception message:
'''%s'''
""" % (expected_message, actual_message))

            return err
        else:
            self.fail("""expected exception %(expected_exception)s not raised
called %(func)r
with args %(args)r
and kwargs %(kwargs)r
""" % locals ())


    # -- Assertions used in more than one class --------------------