Commit 58d0dd92 authored by Claude Paroz's avatar Claude Paroz Committed by Markus Holtermann
Browse files

Refs #24225 -- Added failing test case for removing a previously added field in migrations 

When a related field is deleted, the related model must be updated. As
unchanged models are shared in migration states, the related model must
be re-rendered so that the change applies to a new copy of the related
model.

Thanks Henrik Heimbuerger for the report.
parent ad9ecc2c

tests/migrations/test_state.py

+50 −1
Original line number Diff line number Diff line 
from django.apps.registry import Apps

from django.db import models

from django.db.migrations.operations import RemoveField

from django.db.migrations.operations import DeleteModel, RemoveField

from django.db.migrations.state import (

    InvalidBasesError, ModelState, ProjectState,

)
@@ -366,6 +366,53 @@ class StateTests(TestCase): 
        project_state.add_model(ModelState.from_model(B))

        self.assertEqual(len(project_state.apps.get_models()), 2)



    def test_remove_relations(self):

        """

        #24225 - Tests that relations between models are updated while

        remaining the relations and references for models of an old state.

        """

        class A(models.Model):

            class Meta:

                app_label = "something"



        class B(models.Model):

            to_a = models.ForeignKey(A)



            class Meta:

                app_label = "something"



        def get_model_a(state):

            return [mod for mod in state.apps.get_models() if mod._meta.model_name == 'a'][0]



        project_state = ProjectState()

        project_state.add_model(ModelState.from_model(A))

        project_state.add_model(ModelState.from_model(B))

        self.assertEqual(len(get_model_a(project_state)._meta.related_objects), 1)

        old_state = project_state.clone()



        operation = RemoveField("b", "to_a")

        operation.state_forwards("something", project_state)

        # Tests that model from old_state still has the relation

        model_a_old = get_model_a(old_state)

        model_a_new = get_model_a(project_state)

        self.assertIsNot(model_a_old, model_a_new)

        self.assertEqual(len(model_a_old._meta.related_objects), 1)

        self.assertEqual(len(model_a_new._meta.related_objects), 0)



        # Same test for deleted model

        project_state = ProjectState()

        project_state.add_model(ModelState.from_model(A))

        project_state.add_model(ModelState.from_model(B))

        old_state = project_state.clone()



        operation = DeleteModel("b")

        operation.state_forwards("something", project_state)

        model_a_old = get_model_a(old_state)

        model_a_new = get_model_a(project_state)

        self.assertIsNot(model_a_old, model_a_new)

        self.assertEqual(len(model_a_old._meta.related_objects), 1)

        self.assertEqual(len(model_a_new._meta.related_objects), 0)



    def test_equality(self):

        """

        Tests that == and != are implemented correctly.
@@ -384,11 +431,13 @@ class StateTests(TestCase): 
            {},

            None,

        ))

        project_state.apps  # Fill the apps cached property

        other_state = project_state.clone()

        self.assertEqual(project_state, project_state)

        self.assertEqual(project_state, other_state)

        self.assertEqual(project_state != project_state, False)

        self.assertEqual(project_state != other_state, False)

        self.assertNotEqual(project_state.apps, other_state.apps)



        # Make a very small change (max_len 99) and see if that affects it

        project_state = ProjectState()