'Test IS_DYNAMIC_FIELDNAME with invalid field names'

def testFail(self):

    assertNotEqual = self.assertNotEqual
    requires = IS_DYNAMIC_FIELDNAME()
    (value, error) = requires(None)
    assertNotEqual(error, None)
    (value, error) = requires('')
    assertNotEqual(error, None)
    (value, error) = requires('must    not    contain    blanks')
    assertNotEqual(error, None)
    (value, error) = requires('_must_start_with_letter')
    assertNotEqual(error, None)
    (value, error) = requires('invalid#characters')
    assertNotEqual(error, None)
    (value, error) = requires('id')
    assertNotEqual(error, None)
    (value, error) = requires('modified_by')
    assertNotEqual(error, None)
