CI(pytest): Run tests marked need_solo_run separately (#3879)

* pytest: Create slow and needs_solo_run markers

* python: Apply needs_solo_run marker to two pygrass grid tests

* CI(pytest): Run tests marked need_solo_run separately with a single runner

* pytest: Revert timeout to 300 seconds

.github/workflows/pytest.yml

@@ -73,11 +73,17 @@ jobs:
       - name: Test executing of the grass command
         run: .github/workflows/test_simple.sh
 
-      - name: Run pytest
+      - name: Run pytest with multiple workers in parallel
         run: |
           export PYTHONPATH=`grass --config python_path`:$PYTHONPATH
           export LD_LIBRARY_PATH=$(grass --config path)/lib:$LD_LIBRARY_PATH
-          pytest --verbose --color=yes --durations=0 --durations-min=0.5 --numprocesses auto -ra .
+          pytest --verbose --color=yes --durations=0 --durations-min=0.5 --numprocesses auto -ra . -m 'not needs_solo_run'
+
+      - name: Run pytest with a single worker (for tests marked with needs_solo_run)
+        run: |
+          export PYTHONPATH=`grass --config python_path`:$PYTHONPATH
+          export LD_LIBRARY_PATH=$(grass --config path)/lib:$LD_LIBRARY_PATH
+          pytest --verbose --color=yes --durations=0 --durations-min=0.5 -ra . -m 'needs_solo_run'
 
       - name: Print installed versions
         if: always()

pyproject.toml

@@ -21,6 +21,10 @@ addopts = """
     --ignore='raster/r.category/test_rcategory_doctest.txt'
 """
 timeout = 300
+markers = [
+    "slow: marks tests as slow (deselect with '-m \"not slow\"')",
+    "needs_solo_run: marks tests that must be run without any other tests running in parallel",
+]
 
 
 [tool.bandit]

python/grass/pygrass/modules/tests/grass_pygrass_grid_test.py

@@ -23,6 +23,7 @@ def run_in_subprocess(function):
     process.join()
 
 
+@pytest.mark.needs_solo_run
 @pytest.mark.parametrize("processes", list(range(1, max_processes() + 1)) + [None])
 def test_processes(tmp_path, processes):
     """Check that running with multiple processes works"""
@@ -232,6 +233,7 @@ def run_grid_module():
         assert info["min"] > 0
 
 
+@pytest.mark.needs_solo_run
 @pytest.mark.parametrize(
     "processes, backend",
     [