gh-actions: report release-tests result to Matrix

.github/workflows/release-test.yml

@@ -123,6 +123,7 @@ jobs:
         sudo apt-get install lib32asan6
     - name: Run release tests
       timeout-minutes: 350
+      id: tests
       run: |
         RIOTBASE="$GITHUB_WORKSPACE/RIOT"
         TOX_ARGS=""
@@ -173,6 +174,27 @@ jobs:
         mkdir test-reports/
         junit2html ${REPORT_XML} ${REPORT_NAME}.html
         cp ${REPORT_XML} ${REPORT_NAME}.xml
+    - name: Generate result message
+      if: always()
+      id: generate_results
+      run: |
+        if [ "${{ steps.tests.conclusion }}" == "success" ]; then
+          nice_str=echo "✅ **PASSED**"
+        elif [ "${{ steps.tests.conclusion }}" == "failure" ]; then
+          nice_str="❌ **FAILED**"
+        fi
+        echo "nice_str=${nice_str}" >> ${GITHUB_OUTPUT}
+    - name: Report to Matrix channel
+      if: ${{ always() && steps.generate_results.outputs.nice_str != '' }}
+      uses: fadenb/matrix-chat-message@v0.0.6
+      with:
+        homeserver: matrix.org
+        token: ${{ secrets.RIOT_CI_MATRIX_TOKEN }}
+        channel: '!UXNJuMzHTSAnwntbbN:utwente.io'
+        message: |
+          ${{ steps.generate_results.outputs.nice_str}}: Release tests
+          [${{ matrix.pytest_mark }}, ${{ matrix.sudo }}] on "*${{ github.event_name }}*":
+          ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
     - uses: actions/upload-artifact@v2
       if: always()
       with: