Fixed #23359 -- Added showmigrations command to list migrations and plan.

Thanks to Collin Anderson, Tim Graham, Gabe Jackson, and Marc Tamlyn
for their input, ideas, and review.

2 files changed, 140 insertions, 6 deletions

diff --git a/tests/migrations/test_commands.py b/tests/migrations/test_commands.py
index 5995468e98..a9505dd82e 100644
--- a/tests/migrations/test_commands.py
+++ b/tests/migrations/test_commands.py
@@ -9,8 +9,9 @@ from django.apps import apps
 from django.db import connection, models
 from django.core.management import call_command, CommandError
 from django.db.migrations import questioner
-from django.test import override_settings
+from django.test import ignore_warnings, override_settings
 from django.utils import six
+from django.utils.deprecation import RemovedInDjango20Warning
 from django.utils.encoding import force_text
 
 from .models import UnicodeModel, UnserializableModel
@@ -50,6 +51,15 @@ class MigrateTests(MigrationTestBase):
         self.assertTableNotExists("migrations_tribble")
         self.assertTableNotExists("migrations_book")
 
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_conflict"})
+    def test_migrate_conflict_exit(self):
+        """
+        Makes sure that migrate exits if it detects a conflict.
+        """
+        with self.assertRaisesMessage(CommandError, "Conflicting migrations detected"):
+            call_command("migrate", "migrations")
+
+    @ignore_warnings(category=RemovedInDjango20Warning)
     @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
     def test_migrate_list(self):
         """
@@ -72,13 +82,137 @@ class MigrateTests(MigrationTestBase):
         # Cleanup by unmigrating everything
         call_command("migrate", "migrations", "zero", verbosity=0)
 
-    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_conflict"})
-    def test_migrate_conflict_exit(self):
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
+    def test_showmigrations_list(self):
         """
-        Makes sure that migrate exits if it detects a conflict.
+        Tests --list output of showmigrations command
         """
-        with self.assertRaises(CommandError):
-            call_command("migrate", "migrations")
+        out = six.StringIO()
+        call_command("showmigrations", format='list', stdout=out, verbosity=0)
+        self.assertIn("migrations", out.getvalue().lower())
+        self.assertIn("[ ] 0001_initial", out.getvalue().lower())
+        self.assertIn("[ ] 0002_second", out.getvalue().lower())
+
+        call_command("migrate", "migrations", "0001", verbosity=0)
+
+        out = six.StringIO()
+        # Giving the explicit app_label tests for selective `show_list` in the command
+        call_command("showmigrations", "migrations", format='list', stdout=out, verbosity=0)
+        self.assertIn("migrations", out.getvalue().lower())
+        self.assertIn("[x] 0001_initial", out.getvalue().lower())
+        self.assertIn("[ ] 0002_second", out.getvalue().lower())
+        # Cleanup by unmigrating everything
+        call_command("migrate", "migrations", "zero", verbosity=0)
+
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_run_before"})
+    def test_showmigrations_plan(self):
+        """
+        Tests --plan output of showmigrations command
+        """
+        out = six.StringIO()
+        call_command("showmigrations", format='plan', stdout=out)
+        self.assertIn(
+            "[ ]  migrations.0001_initial\n"
+            "[ ]  migrations.0003_third\n"
+            "[ ]  migrations.0002_second",
+            out.getvalue().lower()
+        )
+
+        out = six.StringIO()
+        call_command("showmigrations", format='plan', stdout=out, verbosity=2)
+        self.assertIn(
+            "[ ]  migrations.0001_initial\n"
+            "[ ]  migrations.0003_third ... (migrations.0001_initial)\n"
+            "[ ]  migrations.0002_second ... (migrations.0001_initial)",
+            out.getvalue().lower()
+        )
+
+        call_command("migrate", "migrations", "0003", verbosity=0)
+
+        out = six.StringIO()
+        call_command("showmigrations", format='plan', stdout=out)
+        self.assertIn(
+            "[x]  migrations.0001_initial\n"
+            "[x]  migrations.0003_third\n"
+            "[ ]  migrations.0002_second",
+            out.getvalue().lower()
+        )
+
+        out = six.StringIO()
+        call_command("showmigrations", format='plan', stdout=out, verbosity=2)
+        self.assertIn(
+            "[x]  migrations.0001_initial\n"
+            "[x]  migrations.0003_third ... (migrations.0001_initial)\n"
+            "[ ]  migrations.0002_second ... (migrations.0001_initial)",
+            out.getvalue().lower()
+        )
+
+        # Cleanup by unmigrating everything
+        call_command("migrate", "migrations", "zero", verbosity=0)
+
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_empty"})
+    def test_showmigrations_plan_no_migrations(self):
+        """
+        Tests --plan output of showmigrations command without migrations
+        """
+        out = six.StringIO()
+        call_command("showmigrations", format='plan', stdout=out)
+        self.assertEqual("", out.getvalue().lower())
+
+        out = six.StringIO()
+        call_command("showmigrations", format='plan', stdout=out, verbosity=2)
+        self.assertEqual("", out.getvalue().lower())
+
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_squashed_complex"})
+    def test_showmigrations_plan_squashed(self):
+        """
+        Tests --plan output of showmigrations command with squashed migrations.
+        """
+        out = six.StringIO()
+        call_command("showmigrations", format='plan', stdout=out)
+        self.assertEqual(
+            "[ ]  migrations.1_auto\n"
+            "[ ]  migrations.2_auto\n"
+            "[ ]  migrations.3_squashed_5\n"
+            "[ ]  migrations.6_auto\n"
+            "[ ]  migrations.7_auto\n",
+            out.getvalue().lower()
+        )
+
+        out = six.StringIO()
+        call_command("showmigrations", format='plan', stdout=out, verbosity=2)
+        self.assertEqual(
+            "[ ]  migrations.1_auto\n"
+            "[ ]  migrations.2_auto ... (migrations.1_auto)\n"
+            "[ ]  migrations.3_squashed_5 ... (migrations.2_auto)\n"
+            "[ ]  migrations.6_auto ... (migrations.3_squashed_5)\n"
+            "[ ]  migrations.7_auto ... (migrations.6_auto)\n",
+            out.getvalue().lower()
+        )
+
+        call_command("migrate", "migrations", "3_squashed_5", verbosity=0)
+
+        out = six.StringIO()
+        call_command("showmigrations", format='plan', stdout=out)
+        self.assertEqual(
+            "[x]  migrations.1_auto\n"
+            "[x]  migrations.2_auto\n"
+            "[x]  migrations.3_squashed_5\n"
+            "[ ]  migrations.6_auto\n"
+            "[ ]  migrations.7_auto\n",
+            out.getvalue().lower()
+        )
+
+        out = six.StringIO()
+        call_command("showmigrations", format='plan', stdout=out, verbosity=2)
+        self.assertEqual(
+            "[x]  migrations.1_auto\n"
+            "[x]  migrations.2_auto ... (migrations.1_auto)\n"
+            "[x]  migrations.3_squashed_5 ... (migrations.2_auto)\n"
+            "[ ]  migrations.6_auto ... (migrations.3_squashed_5)\n"
+            "[ ]  migrations.7_auto ... (migrations.6_auto)\n",
+            out.getvalue().lower()
+        )
 
     @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
     def test_sqlmigrate(self):
diff --git a/tests/migrations/test_migrations_empty/__init__.py b/tests/migrations/test_migrations_empty/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/tests/migrations/test_migrations_empty/__init__.py