[#197] add documentation for creating cassettes

Author: Sonny Bakker

docs/development/index.rst

@@ -0,0 +1,13 @@
+.. _development_index:
+
+Development
+============
+
+**Open Klant** is open-source software. We'd love to have you
+contribute!
+
+.. toctree::
+   :maxdepth: 1
+   :caption: Further reading
+
+   migration

docs/development/migration.rst

@@ -0,0 +1,49 @@
+.. _migration_index:
+
+Migration
+=========
+
+Users of Open Klant version ``1.0.0`` willing to migrate to version ``2.0.0`` or higher
+can make use of the ``migrate_to_v2`` management command. This command **only** migrates
+``Klant`` instances from version ``1.0.0``. The command expects two URLs; a URL for the
+Open Klant instance of version ``1.0.0.``and a URL for version ``2.0.0``. The command
+also expects a ``ACCESS_TOKEN`` environment variable to be set, to authenticate to
+the Open Klant ``1.0.0`` instance. For the ``2.0.0`` instance a dummy token will be
+created.
+
+For this migration, tests are written using VCR, which records the (relevant)
+outgoing requests to cassette files. Whenever tests need to be updated, consider
+re-recording the corresponding cassettes.
+
+To re-record tests, a separate docker compose file is available to run a
+version ``1.0.0`` Open Klant instance next to the ``StaticLiveServer`` (which
+sets up a live server) which runs version ``2.0.0``. The `web` container from the
+docker compose setup should load the corresponding fixture which reside in the
+``migration/fixtures`` folder. A typical workflow, to re-record cassettes,
+could look like the following:
+
+.. code-block:: bash
+
+    # Start the docker compose setup
+    $ docker compose up --detach
+
+    # Load a fixture for a certain test
+    $ docker compose exec -it web \
+        ./src/manage.py loaddata migration/credentials migration/test_digitaal_adres
+
+    # Run the corresponding test
+    $ ./src/manage.py test test openklant.tests.test_migrate.MigrateTestCase.test_digitaal_adres
+
+    # Stop and destroy the containers (to start with a clean slate on the next run)
+    $ docker compose down
+
+
+After running the test a cassette should be created (with the test name as filename)
+in the ``migration/cassettes`` folder.
+
+Note that the docker compose setup, with its fixtures are only needed to (re)create
+cassettes for VCR. The migration tests can be ran without the docker compose setup.
+
+Some tests require custom responses, for example to retrieve the ``subjectIdentificatie``
+when a ``subject`` URL is supplied. For these cases a ``test_server.py`` file is added
+that can be modified as needed to create a response for a cassette.

docs/index.rst

@@ -28,3 +28,4 @@ Open Klant `is`_ and only uses open source.
    :hidden:
 
    installation/index
+   development/index