DOC: Creating a coverage report (#1319)

docs/dev/testing.md

@@ -0,0 +1,23 @@
+# Testing
+
+PyPDF2 uses [`pytest`](https://docs.pytest.org/en/7.1.x/) for testing.
+
+## Creating a Coverage Report
+
+If you want to get a coverage report that considers the Python version specific
+code, you can run [`tox`](https://tox.wiki/en/latest/).
+
+As a prerequisite, we recommend using [`pyenv`](https://github.com/pyenv/pyenv)
+so that you can install the different Python versions:
+
+```
+pyenv install pypy3.8-7.3.7
+pyenv install 3.6.15
+pyenv install 3.7.12
+pyenv install 3.8.12
+pyenv install 3.9.10
+pyenv install 3.10.2
+```
+
+Then you can execute `tox` which will create a coverage report in HTML form
+in the end. The execution takes about 30 minutes.

docs/index.rst

@@ -60,6 +60,7 @@ You can contribute to `PyPDF2 on Github <https://github.com/py-pdf/PyPDF2>`_.
    dev/pdf-format
    dev/cmaps
    dev/deprecations
+   dev/testing
 
 .. toctree::
    :caption: About PyPDF2

tox.ini

@@ -1,11 +1,16 @@
 [tox]
 envlist =
-	py{36,37,38,39,310,py,py3}
+	py{36,37,38,39,310,py3},cov
 
 [testenv]
+setenv=
+    py{36,37,38,39,310,py3}: COVERAGE_FILE={envdir}/.coverage
 deps =
 	pillow
 	pytest
 	pytest-cov
 	pycryptodome
-commands = pytest tests --cov --cov-report term-missing -vv {posargs}
+commands =
+	py{36,37,38,39,310,py3}: pytest tests --cov --cov-report term-missing -vv --no-cov-on-fail {posargs}
+	cov: /usr/bin/env bash -c '{envpython} -m coverage combine {toxworkdir}/py*/.coverage'
+	cov: coverage html --fail-under=85