use file sizes of all dependencies in TestSequencer

CHANGELOG.md

@@ -145,6 +145,7 @@
 
 ### Performance
 
+- `[jest-cli]` Better test order heuristics on first run without cache ([#7553](https://github.com/facebook/jest/pull/7553))
 - `[jest-mock]` Improve `getType` function performance. ([#7159](https://github.com/facebook/jest/pull/7159))
 
 ## 23.6.0

packages/jest-cli/src/TestSequencer.js

@@ -10,9 +10,12 @@
 import type {AggregatedResult} from 'types/TestResult';
 import type {Context} from 'types/Context';
 import type {Test} from 'types/TestRunner';
+import type {Path} from 'types/Config';
 
 import fs from 'fs';
 import HasteMap from 'jest-haste-map';
+import DependencyResolver from 'jest-resolve-dependencies';
+import {buildSnapshotResolver} from 'jest-snapshot';
 
 const FAIL = 0;
 const SUCCESS = 1;
@@ -59,6 +62,30 @@ export default class TestSequencer {
     return cache;
   }
 
+  _fileSizeRecurseDependencies(
+    test: Test,
+    stats: {[path: Path]: number},
+  ): number {
+    const {
+      path,
+      context: {resolver, hasteFS, config},
+    } = test;
+
+    const fileSize = path =>
+      stats[path] || (stats[path] = fs.statSync(path).size);
+
+    const dependencyResolver = new DependencyResolver(
+      resolver,
+      hasteFS,
+      buildSnapshotResolver(config),
+    );
+    return (
+      Array.from(dependencyResolver.resolveRecursive(path))
+        .map(file => fileSize(file))
+        .reduce((sum, size) => sum + size, 0) + fileSize(path)
+    );
+  }
+
   // When running more tests than we have workers available, sort the tests
   // by size - big test files usually take longer to complete, so we run
   // them first in an effort to minimize worker idle time at the end of a
@@ -69,8 +96,6 @@ export default class TestSequencer {
   // fastest results.
   sort(tests: Array<Test>): Array<Test> {
     const stats = {};
-    const fileSize = test =>
-      stats[test.path] || (stats[test.path] = fs.statSync(test.path).size);
     const hasFailed = (cache, test) =>
       cache[test.path] && cache[test.path][0] === FAIL;
     const time = (cache, test) => cache[test.path] && cache[test.path][1];
@@ -90,7 +115,10 @@ export default class TestSequencer {
       } else if (testA.duration != null && testB.duration != null) {
         return testA.duration < testB.duration ? 1 : -1;
       } else {
-        return fileSize(testA) < fileSize(testB) ? 1 : -1;
+        return this._fileSizeRecurseDependencies(testA, stats) <
+          this._fileSizeRecurseDependencies(testB, stats)
+          ? 1
+          : -1;
       }
     });
   }

packages/jest-cli/src/__tests__/test_sequencer.test.js

@@ -11,6 +11,23 @@ import path from 'path';
 import TestSequencer from '../TestSequencer';
 
 jest.mock('fs');
+jest.mock(
+  'jest-resolve-dependencies',
+  () =>
+    class {
+      constructor() {
+        this.resolveRecursive = jest.fn().mockImplementation(
+          path =>
+            ({
+              '/test-a.js': ['/sut-a.js', 'test-util.js'],
+              '/test-ab.js': ['/sut-ab.js'],
+              '/test-b.js': ['/sut-b0.js'],
+              '/test-e.js': ['/sut-e.js'],
+            }[path] || []),
+        );
+      }
+    },
+);
 
 const FAIL = 0;
 const SUCCESS = 1;
@@ -49,10 +66,17 @@ beforeEach(() => {
   fs.writeFileSync = jest.fn();
 });
 
-test('sorts by file size if there is no timing information', () => {
-  expect(sequencer.sort(toTests(['/test-a.js', '/test-ab.js']))).toEqual([
-    {context, duration: undefined, path: '/test-ab.js'},
+test('sorts by dependency file sizes if there is no timing information', () => {
+  expect(sequencer.sort(toTests(['/test-ab.js', '/test-a.js']))).toEqual([
     {context, duration: undefined, path: '/test-a.js'},
+    {context, duration: undefined, path: '/test-ab.js'},
+  ]);
+});
+
+test('includes the test file itself during size calculation', () => {
+  expect(sequencer.sort(toTests(['/test-b.js', '/test-ab.js']))).toEqual([
+    {context, duration: undefined, path: '/test-ab.js'},
+    {context, duration: undefined, path: '/test-b.js'},
   ]);
 });
 
@@ -90,29 +114,29 @@ test('sorts based on failures and timing information', () => {
   ]);
 });
 
-test('sorts based on failures, timing information and file size', () => {
+test('sorts based on failures, timing information and dependency file sizes', () => {
   fs.readFileSync = jest.fn(() =>
     JSON.stringify({
       '/test-a.js': [SUCCESS, 5],
       '/test-ab.js': [FAIL, 1],
-      '/test-c.js': [FAIL],
+      '/test-cd.js': [FAIL],
       '/test-d.js': [SUCCESS, 2],
-      '/test-efg.js': [FAIL],
+      '/test-e.js': [FAIL],
     }),
   );
   expect(
     sequencer.sort(
       toTests([
         '/test-a.js',
         '/test-ab.js',
-        '/test-c.js',
+        '/test-cd.js',
         '/test-d.js',
-        '/test-efg.js',
+        '/test-e.js',
       ]),
     ),
   ).toEqual([
-    {context, duration: undefined, path: '/test-efg.js'},
-    {context, duration: undefined, path: '/test-c.js'},
+    {context, duration: undefined, path: '/test-e.js'},
+    {context, duration: undefined, path: '/test-cd.js'},
     {context, duration: 1, path: '/test-ab.js'},
     {context, duration: 5, path: '/test-a.js'},
     {context, duration: 2, path: '/test-d.js'},