From d0da2820cab495c35eac10680213f927be8b91b0 Mon Sep 17 00:00:00 2001
From: Gordon Pendleton <wgordonw1@gmail.com>
Date: Thu, 26 Mar 2020 05:08:58 -0400
Subject: [PATCH] Fixed #31402 -- Added migrate --check option.

Command exits with non-zero status if unapplied migrations exist.
---
 django/core/management/commands/migrate.py | 10 +++++++
 docs/ref/django-admin.txt                  |  7 +++++
 docs/releases/3.1.txt                      |  3 ++
 tests/migrations/test_commands.py          | 33 ++++++++++++++++++++++
 4 files changed, 53 insertions(+)

diff --git a/django/core/management/commands/migrate.py b/django/core/management/commands/migrate.py
index 575ed47993..85e04b6fcc 100644
--- a/django/core/management/commands/migrate.py
+++ b/django/core/management/commands/migrate.py
@@ -1,3 +1,4 @@
+import sys
 import time
 from importlib import import_module
 
@@ -62,6 +63,10 @@ class Command(BaseCommand):
             '--run-syncdb', action='store_true',
             help='Creates tables for apps without migrations.',
         )
+        parser.add_argument(
+            '--check', action='store_true', dest='check_unapplied',
+            help='Exits with a non-zero status if unapplied migrations exist.',
+        )
 
     @no_translations
     def handle(self, *args, **options):
@@ -143,6 +148,7 @@ class Command(BaseCommand):
             targets = executor.loader.graph.leaf_nodes()
 
         plan = executor.migration_plan(targets)
+        exit_dry = plan and options['check_unapplied']
 
         if options['plan']:
             self.stdout.write('Planned operations:', self.style.MIGRATE_LABEL)
@@ -154,7 +160,11 @@ class Command(BaseCommand):
                     message, is_error = self.describe_operation(operation, backwards)
                     style = self.style.WARNING if is_error else None
                     self.stdout.write('    ' + message, style)
+            if exit_dry:
+                sys.exit(1)
             return
+        if exit_dry:
+            sys.exit(1)
 
         # At this point, ignore run_syncdb if there aren't any apps to sync.
         run_syncdb = options['run_syncdb'] and executor.loader.unmigrated_apps
diff --git a/docs/ref/django-admin.txt b/docs/ref/django-admin.txt
index 56358b4ef8..4011da32fc 100644
--- a/docs/ref/django-admin.txt
+++ b/docs/ref/django-admin.txt
@@ -865,6 +865,13 @@ with hundreds of models.
 Suppresses all user prompts. An example prompt is asking about removing stale
 content types.
 
+.. django-admin-option:: --check
+
+.. versionadded:: 3.1
+
+Makes ``migrate`` exit with a non-zero status when unapplied migrations are
+detected.
+
 ``runserver``
 -------------
 
diff --git a/docs/releases/3.1.txt b/docs/releases/3.1.txt
index 6cbdac4a1e..ecd70feb2e 100644
--- a/docs/releases/3.1.txt
+++ b/docs/releases/3.1.txt
@@ -300,6 +300,9 @@ Management Commands
   enabled for all configured :setting:`DATABASES` by passing the ``database``
   tag to the command.
 
+* The new :option:`migrate --check` option makes the command exit with a
+  non-zero status when unapplied migrations are detected.
+
 Migrations
 ~~~~~~~~~~
 
diff --git a/tests/migrations/test_commands.py b/tests/migrations/test_commands.py
index 14c09c8f98..f7f8a68d4c 100644
--- a/tests/migrations/test_commands.py
+++ b/tests/migrations/test_commands.py
@@ -249,6 +249,39 @@ class MigrateTests(MigrationTestBase):
         with self.assertRaisesMessage(CommandError, "Conflicting migrations detected"):
             call_command("migrate", "migrations")
 
+    @override_settings(MIGRATION_MODULES={
+        'migrations': 'migrations.test_migrations',
+    })
+    def test_migrate_check(self):
+        with self.assertRaises(SystemExit):
+            call_command('migrate', 'migrations', '0001', check_unapplied=True, verbosity=0)
+        self.assertTableNotExists('migrations_author')
+        self.assertTableNotExists('migrations_tribble')
+        self.assertTableNotExists('migrations_book')
+
+    @override_settings(MIGRATION_MODULES={
+        'migrations': 'migrations.test_migrations_plan',
+    })
+    def test_migrate_check_plan(self):
+        out = io.StringIO()
+        with self.assertRaises(SystemExit):
+            call_command(
+                'migrate',
+                'migrations',
+                '0001',
+                check_unapplied=True,
+                plan=True,
+                stdout=out,
+                no_color=True,
+            )
+        self.assertEqual(
+            'Planned operations:\n'
+            'migrations.0001_initial\n'
+            '    Create model Salamander\n'
+            '    Raw Python operation -> Grow salamander tail.\n',
+            out.getvalue(),
+        )
+
     @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
     def test_showmigrations_list(self):
         """