annotate pytest failures on pull-request

.github/workflows/ci-tests.yml

@@ -129,8 +129,12 @@ jobs:
           echo "image.cmap : viridis" >> ${MPL_RC}
           cat ${MPL_RC}
 
+      - if: ${{ matrix.os }} == "ubuntu-latest" and ${{ matrix.python-version }} == "3.10"
+          run: |
+            echo "FLAG_ANNOTATE=--annotate" >> ${GITHUB_ENV}
+
       - name: "iris ${{ matrix.session }}"
         env:
           PY_VER: ${{ matrix.python-version }}
         run: |
-          nox --session ${{ matrix.session }} -- --verbose
+          nox --session ${{ matrix.session }} -- --verbose ${FLAG_ANNOTATE}

noxfile.py

@@ -26,7 +26,7 @@
 #: One specific python version for docs builds
 _PY_VERSION_DOCSBUILD = _PY_VERSION_LATEST
 
-#: Cirrus-CI environment variable hook.
+#: Python environment variable hook.
 PY_VER = os.environ.get("PY_VER", _PY_VERSIONS_ALL)
 
 #: Default cartopy cache directory.
@@ -170,6 +170,12 @@ def prepare_venv(session: nox.sessions.Session) -> None:
             "--explicit",
         )
 
+    # Determine whether to annotate failed tests within CI with a GHA.
+    annotate = "-a" in session.posargs or "--annotate" in session.posargs
+
+    if annotate:
+        session.install("pytest-github-actions-annotate-failures")
+
 
 @nox.session(python=PY_VER, venv_backend="conda")
 def tests(session: nox.sessions.Session):