Docker dev env

CONTRIBUTING.md

@@ -73,6 +73,8 @@ python -X tracemalloc -m unittest -f src/test/test_*
 python -X tracemalloc -m unittest -f src/test/test_runner.py
 ```
 
+To run tests in a dedicated container, see `dev/README.md`.
+
 ## Codestyle
 
 Popper's code is formatted using the [black](https://github.com/psf/black) style. If code does not conform to this style, merges are prevented to the master and this is checked as a CI step.

dev/.gitignore

@@ -0,0 +1 @@
+venv

dev/Dockerfile

@@ -0,0 +1,6 @@
+FROM python:3.8-buster
+
+RUN pip install --upgrade pip
+# black==19.10b0 is the version used in GitHub
+RUN pip install setuptools setuptools_rust virtualenv black==19.10b0
+

dev/README.md

@@ -0,0 +1,20 @@
+# Development environment
+
+The following steps should be executed from within the folder `dev`.
+
+To test popper, build the `popper-dev` image and prepare the folder to hold the venv
+```
+docker-compose build popper-dev
+mkdir venv
+```
+then start the container and install deps into the venv
+```
+docker-compose run --rm popper-dev
+# now you're insided the container
+python -m virtualenv /venv
+source /venv/bin/activate
+pip install -e src/
+```
+From here on, you can always return to the container without having to re-install the venv.
+However, don't forget to activate the venv after entering the container.
+(The container is temporary and will be removed after you leave, so activate the venv each time.)

dev/docker-compose.yml

@@ -0,0 +1,15 @@
+version: '3.7'
+services:
+  popper-dev:
+    image: popper-dev
+    container_name: popper-dev
+    stdin_open: true # docker run -i
+    tty: true        # docker run -t
+    build:
+      context: .
+    command:
+      - bash
+    volumes:
+      - ${PWD}/..:/workspace
+      - ${PWD}/venv:/venv
+    working_dir: /workspace

docs/installation.md

@@ -137,5 +137,7 @@ the above approach you have both (1) popper installed in your machine
 and (2) an environment where you can modify popper and test the 
 results of such modifications.
 
+To create a containerized development environment, e.g. for running tests, see `dev/README.md`.
+
 [venv]: https://virtualenv.pypa.io/en/latest/
 [venv-install]: https://packaging.python.org/guides/installing-using-pip-and-virtual-environments/#installing-virtualenv

pyproject.toml

@@ -0,0 +1,4 @@
+[tool.black]
+exclude='''
+/dev
+'''