'Test IS_DYNAMIC_FIELDTYPE with invalid field types'

def testFail(self):

    assertNotEqual = self.assertNotEqual
    requires = IS_DYNAMIC_FIELDTYPE()
    (value, error) = requires(None)
    assertNotEqual(error, None)
    (value, error) = requires('')
    assertNotEqual(error, None)
    (value, error) = requires('nonsense')
    assertNotEqual(error, None)
    (value, error) = requires('id')
    assertNotEqual(error, None)
    (value, error) = requires('reference    nonexistent_table')
    assertNotEqual(error, None)
