test(ci): run affected-only FE tests via jest --changedSince [experiment]

Experiment on branch test/fe-affected-tests to measure CI time of an
affected-only run. Adds test:affected (jest --changedSince=origin/main)
and switches the FE job to it with fetch-depth: 0 for the merge-base.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: pawelangelow

.github/workflows/tests-frontend.yml

@@ -13,6 +13,9 @@ jobs:
     name: Frontend tests
     steps:
       - uses: actions/checkout@v7.0.0
+        with:
+          # Full history so jest's --changedSince can find the merge-base with main.
+          fetch-depth: 0
 
       - name: Install all libs and dependencies
         uses: ./.github/actions/install-all-build-libs
@@ -35,9 +38,15 @@ jobs:
           FILENAME=$FILENAME DEPS="UI dev" node .github/deps-audit-report.js &&
           curl -H "Content-type: application/json" --data @slack.$FILENAME -H "Authorization: Bearer $SLACK_AUDIT_REPORT_KEY" -X POST https://slack.com/api/chat.postMessage
 
-      - name: Unit tests UI
+      # EXPERIMENT (branch test/fe-affected-tests): run only tests related to
+      # files this branch changed vs main, via jest --changedSince. Measures the
+      # CI time of an affected-only run. No coverage (an affected subset would
+      # trip the global coverageThreshold).
+      - name: Unit tests UI (affected only)
         timeout-minutes: 30
-        run: yarn test:cov --ci --silent
+        run: |
+          git fetch --no-tags origin main
+          yarn test:affected --ci --silent
 
       - name: Upload Test Report
         uses: actions/upload-artifact@v7

package.json

@@ -51,6 +51,7 @@
     "test:api": "yarn --cwd redisinsight/api test",
     "test:api:integration": "yarn --cwd redisinsight/api test:api",
     "test:watch": "jest --watch -w 1",
+    "test:affected": "jest --changedSince=origin/main --passWithNoTests -w 3",
     "test:cov": "cross-env NODE_OPTIONS='' jest --testLocationInResults --json --outputFile=\"report/coverage/report.json\" --silent --coverage --no-cache --forceExit -w 3",
     "test:cov:unit": "jest --group=-component --coverage -w 1",
     "test:cov:component": "jest --group=component --coverage -w 1",