Parallelize Jest in CI

Uses CircleCI's `parallelism` key to split our test jobs across multiple processes, like we do for the build job.
facebook · Aug 6, 2020 · f2b073c · f2b073c
1 parent 32ff428
commit f2b073c
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Showing 4 changed files with 48 additions and 4 deletions.
diff --git a/.circleci/config.yml b/.circleci/config.yml
@@ -19,6 +19,8 @@ aliases:
       name: Install Packages
       command: yarn --frozen-lockfile
 
+  - &TEST_PARALLELISM 20
+
   - &attach_workspace
     at: build
 
@@ -102,6 +104,7 @@ jobs:
   yarn_test:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - *restore_yarn_cache
@@ -111,6 +114,7 @@ jobs:
   RELEASE_CHANNEL_stable_yarn_test_www:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - *restore_yarn_cache
@@ -120,6 +124,7 @@ jobs:
   RELEASE_CHANNEL_stable_yarn_test_www_variant:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - *restore_yarn_cache
@@ -129,6 +134,7 @@ jobs:
   RELEASE_CHANNEL_stable_yarn_test_prod_www:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - *restore_yarn_cache
@@ -138,6 +144,7 @@ jobs:
   RELEASE_CHANNEL_stable_yarn_test_prod_www_variant:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - *restore_yarn_cache
@@ -147,6 +154,7 @@ jobs:
   yarn_test_www:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - *restore_yarn_cache
@@ -156,6 +164,7 @@ jobs:
   yarn_test_www_variant:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - *restore_yarn_cache
@@ -165,6 +174,7 @@ jobs:
   yarn_test_prod_www:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - *restore_yarn_cache
@@ -174,6 +184,7 @@ jobs:
   yarn_test_prod_www_variant:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - *restore_yarn_cache
@@ -183,6 +194,7 @@ jobs:
   RELEASE_CHANNEL_stable_yarn_test_persistent:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
 
     steps:
       - checkout
@@ -193,6 +205,7 @@ jobs:
   RELEASE_CHANNEL_stable_yarn_test_prod:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
 
     steps:
       - checkout
@@ -203,6 +216,7 @@ jobs:
   yarn_test_prod:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - *restore_yarn_cache
@@ -212,7 +226,7 @@ jobs:
   RELEASE_CHANNEL_stable_yarn_build:
     docker: *docker
     environment: *environment
-    parallelism: 20
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - *restore_yarn_cache
@@ -344,6 +358,7 @@ jobs:
   RELEASE_CHANNEL_stable_yarn_test_build:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - attach_workspace: *attach_workspace
@@ -354,6 +369,7 @@ jobs:
   yarn_test_build:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - attach_workspace: *attach_workspace
@@ -404,6 +420,7 @@ jobs:
   RELEASE_CHANNEL_stable_yarn_test_build_prod:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - attach_workspace: *attach_workspace
@@ -414,6 +431,7 @@ jobs:
   yarn_test_build_prod:
     docker: *docker
     environment: *environment
+    parallelism: *TEST_PARALLELISM
     steps:
       - checkout
       - attach_workspace: *attach_workspace

diff --git a/packages/react/src/__tests__/ReactClassEquivalence-test.js b/packages/react/src/__tests__/ReactClassEquivalence-test.js
@@ -34,11 +34,16 @@ function runJest(testFile) {
       'Expected this test to run as a result of one of test commands.',
     );
   }
+
+  const env = Object.assign({}, process.env);
+  // Remove these so that the test file is not filtered out by the mechanism
+  // we use to parallelize tests in CI
+  delete env.CIRCLE_NODE_TOTAL;
+  delete env.CIRCLE_NODE_INDEX;
+
   const result = spawnSync('yarn' + extension, [command, testFile], {
     cwd,
-    env: Object.assign({}, process.env, {
-      REACT_CLASS_EQUIVALENCE_TEST: 'true',
-    }),
+    env,
   });
 
   if (result.error) {

diff --git a/scripts/jest/config.base.js b/scripts/jest/config.base.js
@@ -22,6 +22,8 @@ module.exports = {
   timers: 'fake',
   snapshotSerializers: [require.resolve('jest-snapshot-serializer-raw')],
 
+  testSequencer: require.resolve('./jestSequencer'),
+
   // TODO: Upgrade to Jest 26 which uses jsdom 16 by default.
   testEnvironment: require.resolve('jest-environment-jsdom-sixteen'),
 };
diff --git a/scripts/jest/jestSequencer.js b/scripts/jest/jestSequencer.js
@@ -0,0 +1,19 @@
+'use strict';
+
+const Sequencer = require('@jest/test-sequencer').default;
+
+class CustomSequencer extends Sequencer {
+  sort(tests) {
+    if (process.env.CIRCLE_NODE_TOTAL) {
+      // In CI, parallelize tests across multiple tasks.
+      const nodeTotal = parseInt(process.env.CIRCLE_NODE_TOTAL, 10);
+      const nodeIndex = parseInt(process.env.CIRCLE_NODE_INDEX, 10);
+      tests = tests
+        .sort((a, b) => (a.path < b.path ? -1 : 1))
+        .filter((_, i) => i % nodeTotal === nodeIndex);
+    }
+    return tests;
+  }
+}
+
+module.exports = CustomSequencer;