build: report test failures via Slack (#6539)

* build: report test failures

.github/actions/report/action.yml

+name: Report
+description: Report test failures via Slack
+inputs:
+  name:
+    description: The name of the failing test
+    required: true
+  SLACK_WEBHOOK_URL:
+    description: The webhook URL to send the report to
+    required: true
+
+runs:
+  using: composite
+  steps:
+    - uses: slackapi/slack-github-action@007b2c3c751a190b6f0f040e47ed024deaa72844
+      with:
+        payload: |
+          {
+            "text": "${{ inputs.name }} failing on `${{ github.ref_name }}`",
+            "blocks": [
+              {
+                "type": "section",
+                "text": {
+                  "type": "mrkdwn",
+                  "text": "*${{ inputs.name }} failing on `${{ github.ref_name }}`:* <https://github.com/${{ github.repository}}/actions/runs/${{ github.run_id }}|view failing action>"
+                }
+              },
+              {
+                "type": "section",
+                "text": {
+                  "type": "mrkdwn",
+                  "text": "_This is blocking pull requests and branch promotions._\n_Please prioritize fixing the build._"
+                }
+              }
+            ]
+          }
+      env:
+        SLACK_WEBHOOK_URL: ${{ inputs.SLACK_WEBHOOK_URL }}
+        SLACK_WEBHOOK_TYPE: INCOMING_WEBHOOK
+    # The !oncall bot requires its own message:
+    - uses: slackapi/slack-github-action@007b2c3c751a190b6f0f040e47ed024deaa72844
+      with:
+        payload: |
+          {
+            "text": "!oncall web"
+          }
+      env:
+        SLACK_WEBHOOK_URL: ${{ inputs.SLACK_WEBHOOK_URL }}
+        SLACK_WEBHOOK_TYPE: INCOMING_WEBHOOK

.github/workflows/test.yml

@@ -26,6 +26,11 @@ jobs:
           key: ${{ runner.os }}-eslint-${{ hashFiles('**/yarn.lock') }}-${{ github.run_id }}
           restore-keys: ${{ runner.os }}-eslint-${{ hashFiles('**/yarn.lock') }}-
       - run: yarn lint
+      - if: failure() && github.ref_name == 'main'
+        uses: ./.github/actions/report
+        with:
+          name: Lint
+          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_TEST_REPORTER_WEBHOOK }}
   
   typecheck:
     runs-on: ubuntu-latest
@@ -39,6 +44,11 @@ jobs:
           key: ${{ runner.os }}-tsc-${{ hashFiles('**/yarn.lock') }}-${{ github.run_id }}
           restore-keys: ${{ runner.os }}-tsc-${{ hashFiles('**/yarn.lock') }}-
       - run: yarn typecheck
+      - if: failure() && github.ref_name == 'main'
+        uses: ./.github/actions/report
+        with:
+          name: Typecheck
+          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_TEST_REPORTER_WEBHOOK }}
 
   deps-tests:
     runs-on: ubuntu-latest
@@ -46,6 +56,11 @@ jobs:
       - uses: actions/checkout@v3
       - uses: ./.github/actions/setup
       - run: yarn yarn-deduplicate --strategy=highest --list --fail
+      - if: failure() && github.ref_name == 'main'
+        uses: ./.github/actions/report
+        with:
+          name: Dependency checks
+          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_TEST_REPORTER_WEBHOOK }}
 
   unit-tests:
     runs-on: ubuntu-latest
@@ -65,6 +80,11 @@ jobs:
           fail_ci_if_error: false
           verbose: true
           flags: unit-tests
+      - if: failure() && github.ref_name == 'main'
+        uses: ./.github/actions/report
+        with:
+          name: Unit tests
+          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_TEST_REPORTER_WEBHOOK }}
 
   build-e2e:
     runs-on: ubuntu-latest
@@ -138,9 +158,15 @@ jobs:
 
   # Included as a single job to check for cypress-test-matrix success, as a matrix cannot be checked.
   cypress-tests:
-    if: ${{ always() }}
+    if: always()
     needs: [cypress-test-matrix]
     runs-on: ubuntu-latest
     steps:
+      - uses: actions/checkout@v3
       - if: needs.cypress-test-matrix.result != 'success'
         run: exit 1
+      - if: failure() && github.ref_name == 'main'
+        uses: ./.github/actions/report
+        with:
+          name: Cypress tests
+          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_TEST_REPORTER_WEBHOOK }}