Fixed #25259 -- Added comments to header of generated migration files

tests/migrations/test_writer.py

@@ -12,13 +12,14 @@ import unittest
 import custom_migration_operations.more_operations
 import custom_migration_operations.operations
 
+from django import get_version
 from django.conf import settings
 from django.core.validators import EmailValidator, RegexValidator
 from django.db import migrations, models
 from django.db.migrations.writer import (
     MigrationWriter, OperationWriter, SettingsReference,
 )
-from django.test import SimpleTestCase, ignore_warnings
+from django.test import SimpleTestCase, ignore_warnings, mock
 from django.utils import datetime_safe, six
 from django.utils._os import upath
 from django.utils.deconstruct import deconstructible
@@ -525,6 +526,27 @@ class WriterTests(SimpleTestCase):
             output
         )
 
+    def test_migration_file_header_comments(self):
+        """
+        Test comments at top of file.
+        """
+        migration = type(str("Migration"), (migrations.Migration,), {
+            "operations": []
+        })
+        dt = datetime.datetime(2015, 7, 31, 4, 40, 0, 0, tzinfo=utc)
+        with mock.patch('django.db.migrations.writer.now', lambda: dt):
+            writer = MigrationWriter(migration)
+            output = writer.as_string().decode('utf-8')
+
+        self.assertTrue(
+            output.startswith(
+                "# -*- coding: utf-8 -*-\n"
+                "# Generated by Django %(version)s on 2015-07-31 04:40\n" % {
+                    'version': get_version(),
+                }
+            )
+        )
+
     def test_models_import_omitted(self):
         """
         django.db.models shouldn't be imported if unused.