fix: make sure generated name in config is stable across runs of Jest

packages/jest-config/package.json

@@ -23,8 +23,7 @@
     "jest-validate": "^24.0.0",
     "micromatch": "^3.1.10",
     "pretty-format": "^24.0.0",
-    "realpath-native": "^1.0.2",
-    "uuid": "^3.3.2"
+    "realpath-native": "^1.0.2"
   },
   "engines": {
     "node": ">= 6"

packages/jest-config/src/__tests__/normalize.test.js

@@ -6,16 +6,17 @@
  *
  */
 
+import crypto from 'crypto';
+import path from 'path';
 import {escapeStrForRegex} from 'jest-regex-util';
 import normalize from '../normalize';
 
-jest.mock('jest-resolve');
-jest.mock('path', () => jest.requireActual('path').posix);
+import {DEFAULT_JS_PATTERN} from '../constants';
 
-const path = require('path');
-const DEFAULT_JS_PATTERN = require('../constants').DEFAULT_JS_PATTERN;
 const DEFAULT_CSS_PATTERN = '^.+\\.(css)$';
 
+jest.mock('jest-resolve').mock('path', () => jest.requireActual('path').posix);
+
 let root;
 let expectedPathFooBar;
 let expectedPathFooQux;
@@ -46,16 +47,95 @@ beforeEach(() => {
   require('jest-resolve').findNodeModule = findNodeModule;
 });
 
-it('assigns a random 32-byte hash as a name to avoid clashes', () => {
+it('picks a name based on the rootDir', () => {
+  const rootDir = '/root/path/foo';
+  const expected = crypto
+    .createHash('md5')
+    .update('/root/path/foo')
+    .digest('hex');
+  expect(
+    normalize(
+      {
+        rootDir,
+      },
+      {},
+    ).options.name,
+  ).toBe(expected);
+});
+
+it('picks a name for projects based on the main rootDir', () => {
   const rootDir = '/root/path/foo';
-  const {name: name1} = normalize({rootDir}, {}).options;
-  const {name: name2} = normalize({rootDir}, {}).options;
-
-  expect(name1).toEqual(expect.any(String));
-  expect(name1).toHaveLength(32);
-  expect(name2).toEqual(expect.any(String));
-  expect(name2).toHaveLength(32);
-  expect(name1).not.toBe(name2);
+  const firstExpected = crypto
+    .createHash('md5')
+    .update('/root/path/foo')
+    .digest('hex');
+  const secondExpected = crypto
+    .createHash('md5')
+    .update('/root/path/foo:1')
+    .digest('hex');
+
+  const options = normalize(
+    {
+      projects: [{}, {}],
+      rootDir,
+    },
+    {},
+  );
+
+  expect(options.options.projects[0].name).toBe(firstExpected);
+  expect(options.options.projects[1].name).toBe(secondExpected);
+});
+
+it('picks a name for projects based on the projects rootDir', () => {
+  const firstRootDir = '/root/path/foo';
+  const secondRootDir = '/root/path/bar';
+  const firstExpected = crypto
+    .createHash('md5')
+    .update('/root/path/foo')
+    .digest('hex');
+  const secondExpected = crypto
+    .createHash('md5')
+    .update('/root/path/foo:1')
+    .digest('hex');
+  const thirdExpected = crypto
+    .createHash('md5')
+    .update('/root/path/bar')
+    .digest('hex');
+  const fourthExpected = crypto
+    .createHash('md5')
+    .update('/root/path/baz')
+    .digest('hex');
+
+  const options = normalize(
+    {
+      projects: [
+        {rootDir: firstRootDir},
+        {rootDir: firstRootDir},
+        {rootDir: secondRootDir},
+        {},
+      ],
+      rootDir: '/root/path/baz',
+    },
+    {},
+  );
+
+  expect(options.options.projects[0].name).toBe(firstExpected);
+  expect(options.options.projects[1].name).toBe(secondExpected);
+  expect(options.options.projects[2].name).toBe(thirdExpected);
+  expect(options.options.projects[3].name).toBe(fourthExpected);
+});
+
+it('keeps custom project name based on the projects rootDir', () => {
+  const name = 'test';
+  const options = normalize(
+    {
+      projects: [{name, rootDir: '/path/to/foo'}],
+      rootDir: '/root/path/baz',
+    },
+    {},
+  );
+
+  expect(options.options.projects[0].name).toBe(name);
 });
 
 it('keeps custom names based on the rootDir', () => {
@@ -70,6 +150,16 @@ it('keeps custom names based on the rootDir', () => {
   ).toBe('custom-name');
 });
 
+it('minimal config is stable across runs', () => {
+  const firstNormalization = normalize({rootDir: '/root/path/foo'}, {});
+  const secondNormalization = normalize({rootDir: '/root/path/foo'}, {});
+
+  expect(firstNormalization).toEqual(secondNormalization);
+  expect(JSON.stringify(firstNormalization)).toBe(
+    JSON.stringify(secondNormalization),
+  );
+});
+
 it('sets coverageReporters correctly when argv.json is set', () => {
   expect(
     normalize(

packages/jest-config/src/normalize.js

@@ -17,7 +17,6 @@ import type {
 } from 'types/Config';
 
 import crypto from 'crypto';
-import uuid from 'uuid/v4';
 import glob from 'glob';
 import path from 'path';
 import {ValidationError, validate} from 'jest-validate';
@@ -265,14 +264,33 @@ const normalizePreprocessor = (options: InitialOptions): InitialOptions => {
 };
 
 const normalizeMissingOptions = (options: InitialOptions): InitialOptions => {
+  const knownRootDirs: Set<string> = new Set();
   if (!options.name) {
     options.name = crypto
       .createHash('md5')
       .update(options.rootDir)
-      .update(uuid())
       .digest('hex');
   }
 
+  if (Array.isArray(options.projects)) {
+    options.projects = options.projects.map((project, index) => {
+      if (typeof project !== 'string' && !project.name) {
+        let rootDir = project.rootDir || options.rootDir;
+        if (knownRootDirs.has(rootDir)) {
+          rootDir = `${rootDir}:${index}`;
+        }
+
+        knownRootDirs.add(rootDir);
+        project.name = crypto
+          .createHash('md5')
+          .update(rootDir)
+          .digest('hex');
+      }
+
+      return project;
+    });
+  }
+
   if (!options.setupFiles) {
     options.setupFiles = [];
   }