1. Find container "type" or "language"
2. Add it into tox.ini in envlist, if not present.
3. Create or update a file named test_<container_type>.py (for example, test_python.py)
4. Add your tests there based on testinfra
5. Ensure the container data is up to date by updating matryoshka_tester/data.py.

Just use testinfra documentation (linked above). It should be easy.

You can use the convenience tools from conftest:

• If you are using the "container" fixture, your test will auto generate the right tests for all the versions of your language. This is auto loaded, and doesn't need anything from your side except using the keyword "container". See below for more details.
• If you want to skip some of those tests, use the decorator named restrict_to_version, which accepts a list of strings of the versions for which to run the test. See below for more details.

The container fixture contains the black magic to run commands for all versions of a language container. If you need to run a test only for certain versions of a language stack, you have the following three options (by order of preference):

1. Use the restrict_to_version decorator to limit which containers your test applies to.
2. Create your own fixture
3. Modify the container fixture. The container fixture automatically finds the testfile filename, uses it to infer the language of the container under test, and starts all the necessary containers. See also conftest.py.

This decorator accepts a list of strings matching the versions from data.py.

To use it:

1. add from conftest import restrict_to_version to your imports.
2. wrap your test function as follow (assuming openjdk here):

@restrict_to_version(['11'])
def mytest(container):
    pass

• If you want to restrict certain tests from running in parallel, add the serial mark to the respective function:

@pytest.mark.serial
def test_my_heavy_installation(container):
    ...

In the example above, the test function mytest will only run for the openjdk:11 container, instead of all the containers for openjdk.

$ tox --parallel

$ tox -e testname

testname equals to python for the test file named test_python.py

This will run all the tests for a language, which could mean multiple stacks.