Add rule for django south inconsistent migrations

tests/rules/test_django_south_merge.py

@@ -0,0 +1,43 @@
+import pytest
+from thefuck.rules.django_south_merge import match, get_new_command
+from tests.utils import Command
+
+
+@pytest.fixture
+def stderr():
+    return '''Running migrations for app:
+ ! Migration app:0003_auto... should not have been applied before app:0002_auto__add_field_query_due_date_ but was.
+Traceback (most recent call last):
+  File "/home/nvbn/work/.../bin/python", line 42, in <module>
+    exec(compile(__file__f.read(), __file__, "exec"))
+  File "/home/nvbn/work/.../app/manage.py", line 34, in <module>
+    execute_from_command_line(sys.argv)
+  File "/home/nvbn/work/.../lib/django/core/management/__init__.py", line 443, in execute_from_command_line
+    utility.execute()
+  File "/home/nvbn/work/.../lib/django/core/management/__init__.py", line 382, in execute
+    self.fetch_command(subcommand).run_from_argv(self.argv)
+  File "/home/nvbn/work/.../lib/django/core/management/base.py", line 196, in run_from_argv
+    self.execute(*args, **options.__dict__)
+  File "/home/nvbn/work/.../lib/django/core/management/base.py", line 232, in execute
+    output = self.handle(*args, **options)
+  File "/home/nvbn/work/.../app/lib/south/management/commands/migrate.py", line 108, in handle
+    ignore_ghosts = ignore_ghosts,
+  File "/home/nvbn/work/.../app/lib/south/migration/__init__.py", line 207, in migrate_app
+    raise exceptions.InconsistentMigrationHistory(problems)
+south.exceptions.InconsistentMigrationHistory: Inconsistent migration history
+The following options are available:
+    --merge: will just attempt the migration ignoring any potential dependency conflicts.
+'''
+
+
+def test_match(stderr):
+    assert match(Command('./manage.py migrate', stderr=stderr), None)
+    assert match(Command('python manage.py migrate', stderr=stderr), None)
+    assert not match(Command('./manage.py migrate'), None)
+    assert not match(Command('app migrate', stderr=stderr), None)
+    assert not match(Command('./manage.py test', stderr=stderr), None)
+
+
+def test_get_new_command():
+    assert get_new_command(Command('./manage.py migrate auth'), None) \
+           == './manage.py migrate auth --merge'