GitHub Actions: Fix wait-for-all-tests (#62)

Author: tangrufus

.github/workflows/test.yml

@@ -204,11 +204,13 @@ jobs:
         run: exit 1
 
   wait-for-all-tests:
+    if: cancelled() || contains(needs.*.result, 'cancelled') || contains(needs.*.result, 'failure')
     needs:
       - positive
       - outputs
       - negative
       - missing
     runs-on: ubuntu-latest
     steps:
-      - run: echo "All tests passed!"
+      - name: Assert no required jobs were cancelled or failed
+        run: exit 1