Note! This is a concept/prototype.
You can use the vanilla application image in a docker-stack "wrapped around" the extension directory.
The basic concept is to start an application stack with docker-compose and "host-mount" the extension directly into /vendor/name/extension.
You should be able to use this approach for any Yii 2.0 Framework extension. Note: You need to install the extension in the application. This is a current limitation.
In tests/ resides a docker-compose.yml file, which contains an full-featured phd stack, with pre-installed a Codeception test-framework on the appcli-container.
There are suites for CLI, unit, function and acceptance testing right - ready to use, right out of the box.
The stack also contains Selenium containers for acceptance testing with screenshots - Firefox or Chrome.
Finally it creates a screenshot of that in tests/_output.
docker-compose run phpfpm bash
$ codecept bootstrap
$ codecept run