ci: update lint-and-test.yml (#272)

This pull request updates the `lint-and-test.yml` GitHub Actions
workflow to improve how changes are detected and handled for different
event types. The workflow now better supports merge queue events and
manual runs, ensuring that the correct set of checks is triggered in
each scenario.

Key improvements include:

**Workflow event handling:**

* Added support for the `merge_group` event, enabling the workflow to
run when merge queue checks are requested.

**Change detection logic:**

* Updated the "Detect Changes" job to use different strategies based on
the event type:
- For `merge_group` events, it compares the merge-group head and base
SHAs to detect changes using the `dorny/paths-filter` action.
- For manual (`workflow_dispatch`) runs, it marks all change categories
(`services`, `libs`, `frontend`, `infrastructure`) as changed to ensure
all checks run.
* Modified job outputs to prioritize results from the appropriate
detection step (`filter` or `manual`).

**Minor cleanup:**

* Removed an unnecessary blank line in the `libs` linting job for
clarity.

Author: a-klos

.github/workflows/lint-and-test.yml

@@ -1,6 +1,8 @@
 name: lint-and-test
 
 on:
+  merge_group:
+    types: [checks_requested]
   workflow_dispatch:
 
 env:
@@ -12,20 +14,24 @@ jobs:
     name: Detect Changes
     runs-on: ubuntu-latest
     outputs:
-      services: ${{ steps.changes.outputs.services }}
-      libs: ${{ steps.changes.outputs.libs }}
-      frontend: ${{ steps.changes.outputs.frontend }}
-      infrastructure: ${{ steps.changes.outputs.infrastructure }}
+      services: ${{ steps.filter.outputs.services || steps.manual.outputs.services }}
+      libs: ${{ steps.filter.outputs.libs || steps.manual.outputs.libs }}
+      frontend: ${{ steps.filter.outputs.frontend || steps.manual.outputs.frontend }}
+      infrastructure: ${{ steps.filter.outputs.infrastructure || steps.manual.outputs.infrastructure }}
     steps:
       - name: Checkout
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
-      - name: Detect changes
-        id: changes
+      # When running via merge queue, diff the merge-group head vs its base
+      - name: Detect changes (merge queue)
+        id: filter
+        if: github.event_name == 'merge_group'
         uses: dorny/paths-filter@v3
         with:
+          base: ${{ github.event.merge_group.base_sha }}
+          ref: ${{ github.event.merge_group.head_sha }}
           filters: |
             services:
               - 'services/admin-backend/**'
@@ -40,6 +46,16 @@ jobs:
               - 'infrastructure/**'
               - 'Tiltfile'
 
+      # When run manually, just run everything
+      - name: Mark all as changed (manual run)
+        id: manual
+        if: github.event_name == 'workflow_dispatch'
+        run: |
+          echo "services=true" >> "$GITHUB_OUTPUT"
+          echo "libs=true" >> "$GITHUB_OUTPUT"
+          echo "frontend=true" >> "$GITHUB_OUTPUT"
+          echo "infrastructure=true" >> "$GITHUB_OUTPUT"
+
   sanitize-branch-name:
     runs-on: ubuntu-latest
     outputs:
@@ -111,7 +127,6 @@ jobs:
         run: |
           docker build -t $LINT_IMAGE_NAME --build-arg DIRECTORY=${{ matrix.library }} --build-arg TEST=0 -f libs/Dockerfile libs
 
-
       - name: Run linting
         run: |
           docker run --rm $LINT_IMAGE_NAME make lint