Running application unit test inside a Docker container

Question

I have started to use docker recently and I containerised a python application. I used the following Dockerfile.

FROM python:3.6.5

# working directory
WORKDIR /usr/src/app

# copy requirement file to working directory
COPY requirements.txt ./

RUN pip install --no-cache-dir -r requirements.txt

COPY . .

ENTRYPOINT ["python", "./run.py"]

I have some unit test which I invoke using pytest. I was thinking how I can include this in the docker container such that unit tests would run inside a docker container. Should I build a different image for it. What are your recommendations on it.

Answer 1

You can give

RUN python -m unittest test_file_name.py

or

RUN python -m unittest tests/*

Answer 2

If you have a name of your running container,
you can execute a command on the running container with docker execute

So let's say you want to run some tests through pytest specifying path to tests
on a container called/labeled "my_container":

docker exec my_container pytest ./tests/superstuff/

Note 2 things:

1. The ./ path is relative to your WORKDIR
2. If tests are generating some test/output files, they may have docker-root owner instead of the regular one, if that's not what you want, you can override it with the --user endpoint like so:
   docker exec --user myuser:mygroup my_container pytest ./tests/superstuff/

At least on Linux(Ubuntu), you can also use $(id -u):$(id -g) - to get id&default group of the user running the command