fix: display test duration even if time is mocked out (#7264)

CHANGELOG.md

@@ -54,6 +54,7 @@
 - `[jest-changed-files]` Return correctly the changed files when using `lastCommit=true` on Mercurial repositories ([#7228](https://github.com/facebook/jest/pull/7228))
 - `[babel-jest]` Cache includes babel environment variables ([#7239](https://github.com/facebook/jest/pull/7239))
 - `[jest-config]` Use strings instead of `RegExp` instances in normalized configuration ([#7251](https://github.com/facebook/jest/pull/7251))
+- `[jest-circus]` Make sure to display real duration even if time is mocked ([#7264](https://github.com/facebook/jest/pull/7264))
 
 ### Chore & Maintenance
 

e2e/__tests__/override-globals.test.js

@@ -15,3 +15,14 @@ test('overriding native promise does not freeze Jest', () => {
   const run = runJest('override-globals');
   expect(run.stderr).toMatch(/PASS __tests__(\/|\\)index.js/);
 });
+
+test('has a duration even if time is faked', () => {
+  const regex = /works well \((\d+)ms\)/;
+  const {stderr} = runJest('override-globals', ['--verbose']);
+
+  expect(stderr).toMatch(regex);
+
+  const [, duration] = stderr.match(regex);
+
+  expect(Number(duration)).toBeGreaterThan(0);
+});

e2e/override-globals/package.json

@@ -1,5 +1,8 @@
 {
   "jest": {
-    "testEnvironment": "node"
+    "testEnvironment": "node",
+    "setupFiles": [
+      "<rootDir>/setup.js"
+    ]
   }
 }

e2e/override-globals/setup.js

@@ -0,0 +1,2 @@
+Date.now = () => 0;
+process.hrtime = () => [0, 5000];

packages/jest-circus/src/utils.js

@@ -240,7 +240,7 @@ export const callAsyncCircusFn = (
 
 export const getTestDuration = (test: TestEntry): ?number => {
   const {startedAt} = test;
-  return startedAt ? Date.now() - startedAt : null;
+  return typeof startedAt === 'number' ? Date.now() - startedAt : null;
 };
 
 export const makeRunResult = (

packages/jest-util/src/install_common_globals.js

@@ -18,8 +18,12 @@ const DTRACE = Object.keys(global).filter(key => key.startsWith('DTRACE'));
 export default function(globalObject: Global, globals: ConfigGlobals) {
   globalObject.process = createProcessObject();
 
-  // Keep a reference to "Promise", since "jasmine_light.js" needs it.
-  globalObject[globalObject.Symbol.for('jest-native-promise')] = Promise;
+  const symbol = globalObject.Symbol;
+  // Keep a reference to some globals that Jest needs
+  globalObject[symbol.for('jest-native-promise')] = Promise;
+  globalObject[symbol.for('jest-native-now')] = globalObject.Date.now.bind(
+    globalObject.Date,
+  );
 
   // Forward some APIs.
   DTRACE.forEach(dtrace => {

scripts/babel-plugin-jest-native-promise.js → scripts/babel-plugin-jest-native-globals.js

@@ -14,17 +14,34 @@ module.exports = ({template}) => {
   const promiseDeclaration = template(`
     var Promise = global[Symbol.for('jest-native-promise')] || global.Promise;
   `);
+  const nowDeclaration = template(`
+    var jestNow = global[Symbol.for('jest-native-now')] || global.Date.now;
+  `);
 
   return {
-    name: 'jest-native-promise',
+    name: 'jest-native-globals',
     visitor: {
       ReferencedIdentifier(path, state) {
-        if (path.node.name === 'Promise' && !state.injectedPromise) {
-          state.injectedPromise = true;
+        if (path.node.name === 'Promise' && !state.jestInjectedPromise) {
+          state.jestInjectedPromise = true;
           path
             .findParent(p => p.isProgram())
             .unshiftContainer('body', promiseDeclaration());
         }
+        if (
+          path.node.name === 'Date' &&
+          path.parent.property &&
+          path.parent.property.name === 'now'
+        ) {
+          if (!state.jestInjectedNow) {
+            state.jestInjectedNow = true;
+            path
+              .findParent(p => p.isProgram())
+              .unshiftContainer('body', nowDeclaration());
+          }
+
+          path.parentPath.replaceWithSourceString('jestNow');
+        }
       },
     },
   };

scripts/build.js

@@ -152,9 +152,9 @@ function buildFile(file, silent) {
 
     if (INLINE_REQUIRE_BLACKLIST.test(file)) {
       // The modules in the blacklist are injected into the user's sandbox
-      // We need to guard `Promise` there.
+      // We need to guard some globals there.
       options.plugins.push(
-        require.resolve('./babel-plugin-jest-native-promise')
+        require.resolve('./babel-plugin-jest-native-globals')
       );
     } else {
       // Remove normal plugin.