Readme update

.github/workflows/test_integration.yaml

@@ -2,19 +2,44 @@ name: Tests
 
 on:
   pull_request:
-    branches:
-      - "*"
-  push:
-    branches:
-      - main
+  repository_dispatch:
+    types: [ok-to-test-command]
 
 jobs:
-  tests:
+  # Branch-based pull request
+  integration-trusted:
     runs-on: ubuntu-latest
+    if: github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name == github.repository
     steps:
+
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - name: Run tests
+        env:
+          TEST_SECRET: ${{ secrets.TEST_SECRET }}
+        run: if [[ -z $TEST_SECRET ]]; then exit 1; else echo "OK"; fi
+
+
+  # Repo owner has commented /ok-to-test on a (fork-based) pull request
+  integration-fork:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+      checks: write
+    if: |
+      github.event_name == 'repository_dispatch' &&
+      github.event.client_payload.slash_command.args.named.sha != '' &&
+      contains(
+        github.event.client_payload.pull_request.head.sha,
+        github.event.client_payload.slash_command.args.named.sha
+      )
+    steps:
+
       - uses: actions/checkout@v4
         with:
           persist-credentials: false
+          ref: 'refs/pull/${{ github.event.client_payload.pull_request.number }}/merge'
       - name: Run tests
         env:
           TEST_SECRET: ${{ secrets.TEST_SECRET }}