Add unit testing for migrations

InvenTree/users/test_migrations.py

@@ -0,0 +1,38 @@
+"""
+Unit tests for the user model database migrations
+"""
+
+from django_test_migrations.contrib.unittest_case import MigratorTestCase
+
+from InvenTree import helpers
+
+
+class TestForwardMigrations(MigratorTestCase):
+    """
+    Test entire schema migration sequence for the users app
+    """
+
+    migrate_from = ('users', helpers.getOldestMigrationFile('users'))
+    migrate_to = ('users', helpers.getNewestMigrationFile('users'))
+
+    def prepare(self):
+
+        User = self.old_state.apps.get_model('auth', 'user')
+
+        User.objects.create(
+            username='fred',
+            email='fred@fred.com',
+            password='password'
+        )
+        
+        User.objects.create(
+            username='brad',
+            email='brad@fred.com',
+            password='password'
+        )
+
+    def test_users_exist(self):
+
+        User = self.new_state.apps.get_model('auth', 'user')
+
+        self.assertEqual(User.objects.count(), 2)