[1.7.x] Implement Migration.run_before

This attribute (used for reverse dependencies) was previously declared
and mentioned in the code, but never actually used.

5 files changed, 91 insertions, 0 deletions

diff --git a/tests/migrations/test_loader.py b/tests/migrations/test_loader.py
index 01ead5e8ea..4c1e2d239c 100644
--- a/tests/migrations/test_loader.py
+++ b/tests/migrations/test_loader.py
@@ -102,6 +102,22 @@ class LoaderTests(TestCase):
             ["id", "user"]
         )
 
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_run_before"})
+    def test_run_before(self):
+        """
+        Makes sure the loader uses Migration.run_before.
+        """
+        # Load and test the plan
+        migration_loader = MigrationLoader(connection)
+        self.assertEqual(
+            migration_loader.graph.forwards_plan(("migrations", "0002_second")),
+            [
+                ("migrations", "0001_initial"),
+                ("migrations", "0003_third"),
+                ("migrations", "0002_second"),
+            ],
+        )
+
     @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
     def test_name_match(self):
         "Tests prefix name matching"
diff --git a/tests/migrations/test_migrations_run_before/0001_initial.py b/tests/migrations/test_migrations_run_before/0001_initial.py
new file mode 100644
index 0000000000..7d44a8d789
--- /dev/null
+++ b/tests/migrations/test_migrations_run_before/0001_initial.py
@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    operations = [
+
+        migrations.CreateModel(
+            "Salamander",
+            [
+                ("id", models.AutoField(primary_key=True)),
+                ("size", models.IntegerField(default=0)),
+                ("silly_field", models.BooleanField(default=False)),
+            ],
+        ),
+
+    ]
diff --git a/tests/migrations/test_migrations_run_before/0002_second.py b/tests/migrations/test_migrations_run_before/0002_second.py
new file mode 100644
index 0000000000..c0e03b4620
--- /dev/null
+++ b/tests/migrations/test_migrations_run_before/0002_second.py
@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("migrations", "0001_initial"),
+    ]
+
+    operations = [
+
+        migrations.CreateModel(
+            "Book",
+            [
+                ("id", models.AutoField(primary_key=True)),
+                ("author", models.ForeignKey("migrations.Author", null=True)),
+            ],
+        )
+
+    ]
diff --git a/tests/migrations/test_migrations_run_before/0003_third.py b/tests/migrations/test_migrations_run_before/0003_third.py
new file mode 100644
index 0000000000..d5c098c730
--- /dev/null
+++ b/tests/migrations/test_migrations_run_before/0003_third.py
@@ -0,0 +1,32 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    """
+    This is a wee bit crazy, but it's just to show that run_before works.
+    """
+
+    dependencies = [
+        ("migrations", "0001_initial"),
+    ]
+
+    run_before = [
+        ("migrations", "0002_second"),
+    ]
+
+    operations = [
+
+        migrations.CreateModel(
+            "Author",
+            [
+                ("id", models.AutoField(primary_key=True)),
+                ("name", models.CharField(max_length=255)),
+                ("slug", models.SlugField(null=True)),
+                ("age", models.IntegerField(default=0)),
+            ],
+        )
+
+    ]
diff --git a/tests/migrations/test_migrations_run_before/__init__.py b/tests/migrations/test_migrations_run_before/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/tests/migrations/test_migrations_run_before/__init__.py