Enable parallel jest

.gitlab/ci/frontend.gitlab-ci.yml

@@ -207,7 +207,7 @@ karma-as-if-foss:
   extends: .frontend-job-base
   script:
     - date
-    - yarn jest --ci --coverage
+    - yarn jest --ci --coverage --testSequencer ./scripts/frontend/parallel_ci_sequencer.js
   cache:
     key: jest
     paths:
@@ -229,6 +229,7 @@ jest:
       - tmp/tests/frontend/
     reports:
       junit: junit_jest.xml
+  parallel: 2
 
 jest-as-if-foss:
   extends:

scripts/frontend/parallel_ci_sequencer.js

+const Sequencer = require('@jest/test-sequencer').default;
+
+class ParallelCISequencer extends Sequencer {
+  constructor() {
+    super();
+    this.ciNodeIndex = parseInt(process.env.CI_NODE_INDEX || '1');
+    this.ciNodeTotal = parseInt(process.env.CI_NODE_TOTAL || '1');
+  }
+
+  sort(tests) {
+    const testsForThisRunner = this.distributeAcrossCINodes(tests);
+
+    console.log(`CI_NODE_INDEX: ${this.ciNodeIndex}`);
+    console.log(`CI_NODE_TOTAL: ${this.ciNodeTotal}`);
+    console.log(`Total number of tests: ${tests.length}`);
+    console.log(`Total number of tests for this runner: ${testsForThisRunner.length}`);
+
+    return super.sort(testsForThisRunner);
+  }
+
+  distributeAcrossCINodes(tests) {
+    return tests.filter((test, index) => {
+      return index % this.ciNodeTotal === this.ciNodeIndex - 1;
+    });
+  }
+}
+
+module.exports = ParallelCISequencer;