Merge lp:~elachuni/u1-test-utils/migration-tests into lp:u1-test-utils

[Anthony Lenton]

Overview
========
This branch adds a drop-in migration test case that can be applied to all our projects.

Details
=======
The new MigrationTestCase basically runs all migrations forwards and backwards again, to ensure that they run correctly.
A future improvement would be to add frozen fixtures that can be loaded after each migration, to ensure that the DB schema is left in a sane state.

While I was there, I renamed canonical.isd to isdutils, so that we're not using namespace packages as agreed in our team tech call.

[Vincent Ladeuil (vila)]

Unfortunately this mp seems to be abandoned, marking as rejected to clear the queue, feel free to mark needs review with an explanation if needed.

review: Needs Fixing

Unmerged revisions

2. By Anthony Lenton on 2011-03-30

Renamed canonical.isd package to isdutils.

Added MigrationTestCase, that should be a drop-in test for migrations in all our projects.

=== removed directory 'canonical'
=== removed file 'canonical/__init__.py'
--- canonical/__init__.py	2011-02-07 16:48:09 +0000
+++ canonical/__init__.py	1970-01-01 00:00:00 +0000
@@ -1,5 +0,0 @@
-from pkgutil import extend_path
-
-
-# denote package as namespace package
-__path__ = extend_path(__path__, __name__)

=== renamed directory 'canonical/isd' => 'isdutils'
=== added file 'isdutils/tests/migrations.py'
--- isdutils/tests/migrations.py	1970-01-01 00:00:00 +0000
+++ isdutils/tests/migrations.py	2011-03-30 14:26:01 +0000
@@ -0,0 +1,75 @@
+# A standard test case for checking migrations.  Just import MigrationTestCase
+# from your tests' __init__.py
+
+from __future__ import absolute_import
+
+__all__ = [
+    'MigrationTestCase',
+]
+
+import os
+
+from django.conf import settings
+from django.core import management
+from django.db import connection
+from south import migration, orm
+
+from isdutils.tests.django import switch_settings
+from isdutils.tests.logging import LogHandlerTestCase
+
+class MigrationTestCase(LogHandlerTestCase):
+    def setUp(self):
+        self.test_db_name = '/tmp/migrations_test.sql'
+        patched_settings = {
+            'DATABASE_NAME': self.test_db_name,
+            'DATABASE_ENGINE': 'sqlite3',
+        }
+        self.orig_settings = switch_settings(**patched_settings)
+        connection.settings_dict.update(patched_settings)
+        self.orig_connection = connection.connection
+        connection.connection = None
+        management._commands['syncdb'] = 'south'
+
+    def patch_hacky_sqlite3_cludge(self):
+        """Work around a South sqlite3 hack with another even hackier one.
+
+        As Sqlite3 doesn't support altering or deleting a column, South
+        simulates this by creating a new table with the new columns, copying
+        over the data and then putting the new table in the old one's place.
+
+        South 0.6 does this at most once for each migration, so the new table
+        is remade the first time any column is deleted or altered.
+
+        So's to remember that it has already remade a table it stores a class
+        attribute *on the orm model itself*.  As South's orm stores one model
+        per migration, this works fine as long as each migration is run
+        at most once per process, in any direction.
+
+        To be able to run migrations multiple times here, we invalidate the
+        orm's cache after any run.
+
+        Luckily this hack won't be needed in South 0.7.
+        """
+        orm._orm_cache = {}
+
+    def tearDown(self):
+        switch_settings(**self.orig_settings)
+        connection.settings_dict.update(self.orig_settings)
+        connection.connection = self.orig_connection
+        if os.path.exists(self.test_db_name):
+            os.remove(self.test_db_name)
+        management._commands['syncdb'] = 'django.core'
+
+    def test_migrations_straight_forwards(self):
+        """Run migrations forwards from an empty DB"""
+        management.call_command('syncdb', migrate=True, interactive=False,
+            verbosity=0)
+        self.patch_hacky_sqlite3_cludge()
+
+    def test_migrations_straight_backwards(self):
+        """Run migrations backwards, from an fully migrated DB"""
+        management.call_command('syncdb', migrate=True, interactive=False,
+            verbosity=0)
+        self.patch_hacky_sqlite3_cludge()
+        management.call_command('migrate', target='zero', verbosity=0)
+        self.patch_hacky_sqlite3_cludge()

=== modified file 'setup.py'
--- setup.py	2011-02-08 20:15:31 +0000
+++ setup.py	2011-03-30 14:26:01 +0000
@@ -8,7 +8,7 @@
 def get_version():
     version = [
         (line.split('=')[1]).strip().strip('"').strip("'")
-        for line in open(os.path.join('canonical', 'isd', '__init__.py'))
+        for line in open(os.path.join('isdutils', '__init__.py'))
         if line.startswith( '__version__' )
     ][0]
     return version