Fixed #27844 -- Added optimizemigration management command.

tests/migrations/test_commands.py

@@ -2810,3 +2810,163 @@ class AppLabelErrorTests(TestCase):
     def test_squashmigrations_app_name_specified_as_label(self):
         with self.assertRaisesMessage(CommandError, self.did_you_mean_auth_error):
             call_command("squashmigrations", "django.contrib.auth", "0002")
+
+    def test_optimizemigration_nonexistent_app_label(self):
+        with self.assertRaisesMessage(CommandError, self.nonexistent_app_error):
+            call_command("optimizemigration", "nonexistent_app", "0002")
+
+    def test_optimizemigration_app_name_specified_as_label(self):
+        with self.assertRaisesMessage(CommandError, self.did_you_mean_auth_error):
+            call_command("optimizemigration", "django.contrib.auth", "0002")
+
+
+class OptimizeMigrationTests(MigrationTestBase):
+    def test_no_optimization_possible(self):
+        out = io.StringIO()
+        with self.temporary_migration_module(
+            module="migrations.test_migrations"
+        ) as migration_dir:
+            call_command(
+                "optimizemigration", "migrations", "0002", stdout=out, no_color=True
+            )
+            migration_file = os.path.join(migration_dir, "0002_second.py")
+            self.assertTrue(os.path.exists(migration_file))
+            call_command(
+                "optimizemigration",
+                "migrations",
+                "0002",
+                stdout=out,
+                no_color=True,
+                verbosity=0,
+            )
+        self.assertEqual(out.getvalue(), "No optimizations possible.\n")
+
+    def test_optimization(self):
+        out = io.StringIO()
+        with self.temporary_migration_module(
+            module="migrations.test_migrations"
+        ) as migration_dir:
+            call_command(
+                "optimizemigration", "migrations", "0001", stdout=out, no_color=True
+            )
+            initial_migration_file = os.path.join(migration_dir, "0001_initial.py")
+            self.assertTrue(os.path.exists(initial_migration_file))
+            with open(initial_migration_file) as fp:
+                content = fp.read()
+                self.assertIn(
+                    '("bool", models.BooleanField'
+                    if HAS_BLACK
+                    else "('bool', models.BooleanField",
+                    content,
+                )
+        self.assertEqual(
+            out.getvalue(),
+            f"Optimizing from 4 operations to 2 operations.\n"
+            f"Optimized migration {initial_migration_file}\n",
+        )
+
+    def test_optimization_no_verbosity(self):
+        out = io.StringIO()
+        with self.temporary_migration_module(
+            module="migrations.test_migrations"
+        ) as migration_dir:
+            call_command(
+                "optimizemigration",
+                "migrations",
+                "0001",
+                stdout=out,
+                no_color=True,
+                verbosity=0,
+            )
+            initial_migration_file = os.path.join(migration_dir, "0001_initial.py")
+            self.assertTrue(os.path.exists(initial_migration_file))
+            with open(initial_migration_file) as fp:
+                content = fp.read()
+                self.assertIn(
+                    '("bool", models.BooleanField'
+                    if HAS_BLACK
+                    else "('bool', models.BooleanField",
+                    content,
+                )
+        self.assertEqual(out.getvalue(), "")
+
+    def test_creates_replace_migration_manual_porting(self):
+        out = io.StringIO()
+        with self.temporary_migration_module(
+            module="migrations.test_migrations_manual_porting"
+        ) as migration_dir:
+            call_command(
+                "optimizemigration", "migrations", "0003", stdout=out, no_color=True
+            )
+            optimized_migration_file = os.path.join(
+                migration_dir, "0003_third_optimized.py"
+            )
+            self.assertTrue(os.path.exists(optimized_migration_file))
+            with open(optimized_migration_file) as fp:
+                content = fp.read()
+                self.assertIn("replaces = [", content)
+        self.assertEqual(
+            out.getvalue(),
+            f"Optimizing from 3 operations to 2 operations.\n"
+            f"Manual porting required\n"
+            f"  Your migrations contained functions that must be manually copied over,"
+            f"\n"
+            f"  as we could not safely copy their implementation.\n"
+            f"  See the comment at the top of the optimized migration for details.\n"
+            f"Optimized migration {optimized_migration_file}\n",
+        )
+
+    def test_fails_squash_migration_manual_porting(self):
+        out = io.StringIO()
+        with self.temporary_migration_module(
+            module="migrations.test_migrations_manual_porting"
+        ) as migration_dir:
+            msg = (
+                "Migration will require manual porting but is already a squashed "
+                "migration.\nTransition to a normal migration first: "
+                "https://docs.djangoproject.com/en/dev/topics/migrations/"
+                "#squashing-migrations"
+            )
+            with self.assertRaisesMessage(CommandError, msg):
+                call_command("optimizemigration", "migrations", "0004", stdout=out)
+            optimized_migration_file = os.path.join(
+                migration_dir, "0004_fourth_optimized.py"
+            )
+            self.assertFalse(os.path.exists(optimized_migration_file))
+        self.assertEqual(
+            out.getvalue(), "Optimizing from 3 operations to 2 operations.\n"
+        )
+
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
+    def test_optimizemigration_check(self):
+        with self.assertRaises(SystemExit):
+            call_command(
+                "optimizemigration", "--check", "migrations", "0001", verbosity=0
+            )
+
+        call_command("optimizemigration", "--check", "migrations", "0002", verbosity=0)
+
+    @override_settings(
+        INSTALLED_APPS=["migrations.migrations_test_apps.unmigrated_app_simple"],
+    )
+    def test_app_without_migrations(self):
+        msg = "App 'unmigrated_app_simple' does not have migrations."
+        with self.assertRaisesMessage(CommandError, msg):
+            call_command("optimizemigration", "unmigrated_app_simple", "0001")
+
+    @override_settings(
+        MIGRATION_MODULES={"migrations": "migrations.test_migrations_clashing_prefix"},
+    )
+    def test_ambigious_prefix(self):
+        msg = (
+            "More than one migration matches 'a' in app 'migrations'. Please "
+            "be more specific."
+        )
+        with self.assertRaisesMessage(CommandError, msg):
+            call_command("optimizemigration", "migrations", "a")
+
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
+    def test_unknown_prefix(self):
+        msg = "Cannot find a migration matching 'nonexistent' from app 'migrations'."
+        with self.assertRaisesMessage(CommandError, msg):
+            call_command("optimizemigration", "migrations", "nonexistent")