How can I test a form's validation logic in a unit test driver in Django?

I want to test the is_valid portion of a form's validation logic. In my test driver I have:

  test_开发者_如何学Pythonanimal = Animal(name="cat", number_paws="4")
  test_animal_form = AnimalForm(instance=test_animal)
  assertEqual(test_animal_form.is_valid(), True)

The assertion fails, but from what I see there shouldn't be any errors in the form. I don't see any validation errors in the form. Should this work as a test case if the test_animal instance when loaded into the form should validate?

The reason you're seeing the validation errors is because instance data isn't used in validation, you have to specify the data being sent to the form.

test_animal = Animal(name="cat", number_paws="4")
test_animal_form = AnimalForm(instance=test_animal)
assertEqual(test_animal_form.is_valid(), False) # No data has been supplied yet.
test_animal_form = AnimalForm({'name': "cat", 'number_paws': 4, }, instance=test_animal)
assertEqual(test_animal_form.is_valid(), True) # Now that you have given it data, it can validate.