Implement async_hooks manually

docs/CLI.md

@@ -177,7 +177,7 @@ Print debugging info about your Jest config.
 Attempt to collect and print open handles preventing Jest from exiting cleanly.
 Use this in cases where you need to use `--forceExit` in order for Jest to exit
 to potentially track down the reason. Implemented using
-[`why-is-node-running`](https://github.com/mafintosh/why-is-node-running), so it
+[`async_hooks`](https://nodejs.org/api/async_hooks.html), so it
 only works in Node 8 and newer.
 
 ### `--env=<environment>`

docs/Configuration.md

@@ -963,10 +963,7 @@ structure as the first argument and return it:
   "numPassedTests": number,
   "numFailedTests": number,
   "numPendingTests": number,
-  "openHandles": Array<{
-     title: string,
-     entries: Array<{file: string, line: string}>,
-  }>,
+  "openHandles": Array<Error>,
   "testResults": [{
     "numFailingTests": number,
     "numPassingTests": number,

packages/jest-cli/package.json

@@ -39,9 +39,6 @@
     "which": "^1.2.12",
     "yargs": "^11.0.0"
   },
-  "optionalDependencies": {
-    "why-is-node-running": "^2.0.2"
-  },
   "bin": {
     "jest": "./bin/jest.js"
   },

packages/jest-cli/src/cli/index.js

@@ -14,13 +14,13 @@ import type {GlobalConfig, Path, ProjectConfig} from 'types/Config';
 import {Console, clearLine, createDirectory} from 'jest-util';
 import {validateCLIOptions} from 'jest-validate';
 import {readConfig, deprecationEntries} from 'jest-config';
-import {formatStackTrace} from 'jest-message-util';
 import {version as VERSION} from '../../package.json';
 import * as args from './args';
 import chalk from 'chalk';
 import createContext from '../lib/create_context';
 import exit from 'exit';
 import getChangedFilesPromise from '../get_changed_files_promise';
+import {formatHandleErrors} from '../get_node_handles';
 import fs from 'fs';
 import handleDeprecationWarnings from '../lib/handle_deprecation_warnings';
 import logDebugMessages from '../lib/log_debug_messages';
@@ -106,27 +106,12 @@ export const runCLI = async (
   const {openHandles} = results;
 
   if (openHandles && openHandles.length) {
-    const handles = openHandles
-      .map(({title, entries}) => ({
-        // Fake column to make it a valid stack trace
-        stack: entries.map(({file}) => `at ${file}:0`).join('\n'),
-        title,
-      }))
-      .map(
-        ({title, stack}) =>
-          title +
-          '\n' +
-          // First config should be fine
-          formatStackTrace(stack, configs[0], {noStackTrace: false}),
-      )
-      .join('\n\n');
-
     const openHandlesString = pluralize('open handle', openHandles.length, 's');
 
     const message =
       chalk.red(
         `\nJest has detected the following ${openHandlesString} potentially keeping Jest from exiting:\n\n`,
-      ) + handles;
+      ) + formatHandleErrors(openHandles, configs[0]).join('\n\n');
 
     console.error(message);
   }

packages/jest-cli/src/get_node_handles.js

@@ -0,0 +1,83 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+import type {ProjectConfig} from 'types/Config';
+
+// This works for nodes without the async_hooks as the require's lazy
+// $FlowFixMe: Node core module
+import asyncHooks from 'async_hooks';
+
+import {
+  formatStackTrace,
+  separateMessageFromStack,
+} from '../../jest-message-util/build';
+
+// Inspired by https://github.com/mafintosh/why-is-node-running/blob/master/index.js
+// Extracted as we want to format the result ourselves
+export default function collectHandles(): () => Array<Error> {
+  const activeHandles: Map<string, Error> = new Map();
+
+  function initHook(asyncId, type) {
+    if (type === 'TIMERWRAP') return;
+    const error = new Error(type);
+
+    if (Error.captureStackTrace) {
+      Error.captureStackTrace(error, initHook);
+    }
+
+    if (error.stack.includes('Runtime.requireModule')) {
+      activeHandles.set(asyncId, error);
+    }
+  }
+
+  let hook;
+
+  try {
+    hook = asyncHooks.createHook({
+      destroy(asyncId) {
+        activeHandles.delete(asyncId);
+      },
+      init: initHook,
+    });
+
+    hook.enable();
+  } catch (e) {
+    const nodeMajor = Number(process.versions.node.split('.')[0]);
+    if (e.code === 'MODULE_NOT_FOUND' && nodeMajor < 8) {
+      throw new Error(
+        'You can only use --detectOpenHandles on Node 8 and newer.',
+      );
+    } else {
+      throw e;
+    }
+  }
+
+  return () => {
+    hook.disable();
+
+    const result = Array.from(activeHandles.values());
+
+    activeHandles.clear();
+
+    return result;
+  };
+}
+
+export function formatHandleErrors(
+  errors: Array<Error>,
+  config: ProjectConfig,
+): Array<string> {
+  return errors.map(err => {
+    const {message, stack} = separateMessageFromStack(err.stack);
+
+    return (
+      message + '\n\n' + formatStackTrace(stack, config, {noStackTrace: false})
+    );
+  });
+}

packages/jest-cli/src/run_jest.js

@@ -26,7 +26,7 @@ import TestSequencer from './test_sequencer';
 import {makeEmptyAggregatedTestResult} from './test_result_helpers';
 import FailedTestsCache from './failed_tests_cache';
 import JestHooks, {type JestHookEmitter} from './jest_hooks';
-import formatWhyRunning from './format_why_node_running';
+import collectNodeHandles from './get_node_handles';
 
 const setConfig = (contexts, newConfig) =>
   contexts.forEach(
@@ -75,11 +75,11 @@ const processResults = (runResults, options) => {
     onComplete,
     outputStream,
     testResultsProcessor,
-    whyRunning,
+    collectHandles,
   } = options;
 
-  if (whyRunning) {
-    runResults.openHandles = formatWhyRunning(whyRunning);
+  if (collectHandles) {
+    runResults.openHandles = collectHandles();
   } else {
     runResults.openHandles = [];
   }
@@ -254,21 +254,10 @@ export default (async function runJest({
   // paths when printing.
   setConfig(contexts, {cwd: process.cwd()});
 
-  let whyRunning;
+  let collectHandles;
 
   if (globalConfig.detectOpenHandles) {
-    try {
-      whyRunning = require('why-is-node-running');
-    } catch (e) {
-      const nodeMajor = Number(process.versions.node.split('.')[0]);
-      if (e.code === 'MODULE_NOT_FOUND' && nodeMajor < 8) {
-        throw new Error(
-          'You can only use --detectOpenHandles on Node 8 and newer.',
-        );
-      } else {
-        throw e;
-      }
-    }
+    collectHandles = collectNodeHandles();
   }
 
   if (globalConfig.globalSetup) {
@@ -308,11 +297,11 @@ export default (async function runJest({
     await globalTeardown();
   }
   return processResults(results, {
+    collectHandles,
     isJSON: globalConfig.json,
     onComplete,
     outputFile: globalConfig.outputFile,
     outputStream,
     testResultsProcessor: globalConfig.testResultsProcessor,
-    whyRunning,
   });
 });

types/TestResult.js

@@ -122,7 +122,7 @@ export type AggregatedResultWithoutCoverage = {
   numRuntimeErrorTestSuites: number,
   numTotalTests: number,
   numTotalTestSuites: number,
-  openHandles: Array<OpenHandle>,
+  openHandles: Array<Error>,
   snapshot: SnapshotSummary,
   startTime: number,
   success: boolean,
@@ -140,11 +140,6 @@ export type Suite = {|
   tests: Array<AssertionResult>,
 |};
 
-export type OpenHandle = {|
-  title: string,
-  entries: Array<{file: string, line: string}>,
-|};
-
 export type TestResult = {|
   console: ?ConsoleBuffer,
   coverage?: RawCoverage,
@@ -155,7 +150,7 @@ export type TestResult = {|
   numFailingTests: number,
   numPassingTests: number,
   numPendingTests: number,
-  openHandles: Array<OpenHandle>,
+  openHandles: Array<Error>,
   perfStats: {|
     end: Milliseconds,
     start: Milliseconds,

yarn.lock

@@ -8790,10 +8790,6 @@ stack-utils@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/stack-utils/-/stack-utils-1.0.1.tgz#d4f33ab54e8e38778b0ca5cfd3b3afb12db68620"
 
-[email protected]:
-  version "0.0.2"
-  resolved "https://registry.yarnpkg.com/stackback/-/stackback-0.0.2.tgz#1ac8a0d9483848d1695e418b6d031a3c3ce68e3b"
-
 stacktrace-parser@^0.1.3:
   version "0.1.4"
   resolved "https://registry.yarnpkg.com/stacktrace-parser/-/stacktrace-parser-0.1.4.tgz#01397922e5f62ecf30845522c95c4fe1d25e7d4e"
@@ -9673,12 +9669,6 @@ which@^1.2.1, which@^1.2.12, which@^1.2.14, which@^1.2.9, which@^1.3.0:
   dependencies:
     isexe "^2.0.0"
 
-why-is-node-running@^2.0.2:
-  version "2.0.2"
-  resolved "https://registry.yarnpkg.com/why-is-node-running/-/why-is-node-running-2.0.2.tgz#faf352f095356c8c37a28bf645f874e5648c8d02"
-  dependencies:
-    stackback "0.0.2"
-
 wide-align@^1.1.0:
   version "1.1.2"
   resolved "https://registry.yarnpkg.com/wide-align/-/wide-align-1.1.2.tgz#571e0f1b0604636ebc0dfc21b0339bbe31341710"