Improve coverage report

First enable coverage for child processes, so we get coverage report
from the drenv tool and from script run by the drenv tool. This is a bit
tricky, requiring enabling coverage for child process using a .pth file
and using coverage parallel mode, combining output from multiple
processes.

With this change we report now all code running during the tests:

    $ make coverage
    python3 -m coverage report
    Name                  Stmts   Miss  Cover
    -----------------------------------------
    drenv/__init__.py        77     48    38%
    drenv/__main__.py       109     23    79%
    drenv/clusteradm.py      41     41     0%
    drenv/commands.py        93      2    98%
    drenv/envfile.py         80      0   100%
    drenv/kubectl.py         31      0   100%
    -----------------------------------------
    TOTAL                   431    114    74%

Part-of: #677
Signed-off-by: Nir Soffer <[email protected]>

.github/workflows/sanity.yml

@@ -100,6 +100,9 @@ jobs:
       - name: Install tools
         run: pip install -r test/requirements.txt
 
+      - name: Enable coverage for child processes
+        run: cp test/coverage.pth $(python -m site --user-site)
+
       - name: Install drenv
         run: pip install -e test
 

.gitignore

@@ -34,4 +34,5 @@ config/hub/bundle
 test/drenv.egg-info/
 test/**/__pycache__/
 test/.coverage
+test/.coverage.*
 test/.vimrc

test/.coveragerc

@@ -0,0 +1,4 @@
+[run]
+parallel = True
+source = drenv
+omit = drenv/*_test.py

test/Makefile

@@ -13,7 +13,9 @@ black-reformat:
 	python3 -m black drenv */start */test
 
 test:
-	python3 -m coverage run --source drenv -m pytest
+	rm -f .coverage.*
+	COVERAGE_PROCESS_START=.coveragerc python3 -m coverage run -m pytest
+	python3 -m coverage combine --quiet
 
 coverage:
 	python3 -m coverage report

test/README.md

@@ -509,6 +509,15 @@ This is a configuration for testing regional DR using a hub cluster and
 pip install -r requirements.txt
 ```
 
+### Enabling full test coverage
+
+To enable test coverage for child processes, copy the `coverage.pth`
+file to the python installation:
+
+```
+cp coverage.pth ~/.venv/ramen/lib/python*/site-packages
+```
+
 ### Running the tests
 
 Run all linters and tests and report test coverage:

test/coverage.pth

@@ -0,0 +1 @@
+import coverage; coverage.process_startup()