correct test.yml to run slack for assigned contributors

.github/workflows/test.yml

@@ -55,8 +55,18 @@ jobs:
         with:
           needs_context: ${{ toJson(needs) }}
           github_token: ${{ secrets.GITHUB_TOKEN }}
+      - name: Check if secret exists
+        id: check_secret
+        env:
+          SLACK_WEBHOOK: ${{ secrets.SLACK_ROBOTICS_CI_WEBHOOK }}
+        run: |
+          if [[ -z "$SLACK_WEBHOOK" ]]; then
+            echo "slack_webhook_exists=false" >> $GITHUB_ENV
+          else
+            echo "slack_webhook_exists=true" >> $GITHUB_ENV
+          fi
       - name: Slack workflow notification
-        if: steps.should_notify.outputs.should_send_message == 'yes'
+        if: steps.should_notify.outputs.should_send_message == 'yes' && env.slack_webhook_exists == 'true'
         uses: Gamesight/slack-workflow-status@master
         with:
           repo_token: ${{ secrets.GITHUB_TOKEN }}