fix: jest-circus shares events among imports #11483

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Fixes
 
+- `[jest-circus]` Shares events with event handlers among imports ([#11483](https://github.com/facebook/jest/pull/11483))
 - `[jest-reporter]` Allow `node-notifier@10` as peer dependency ([#11523](https://github.com/facebook/jest/pull/11523))
 - `[jest-reporter]` Update `v8-to-istanbul` ([#11523](https://github.com/facebook/jest/pull/11523))
 

packages/jest-circus/src/__mocks__/testUtils.ts

@@ -46,6 +46,7 @@ export const runTest = (source: string) => {
 
     const testEventHandler = require('${TEST_EVENT_HANDLER_PATH}').default;
     const addEventHandler = require('${CIRCUS_STATE_PATH}').addEventHandler;
+    const removeEventHandler = require('${CIRCUS_STATE_PATH}').removeEventHandler;
     addEventHandler(testEventHandler);
 
     ${source};

packages/jest-circus/src/__tests__/__snapshots__/eventHandler.test.ts.snap

@@ -0,0 +1,39 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`addEventHandler registers a callback with events 1`] = `
+start_describe_definition: describe
+add_test: receives events
+finish_describe_definition: describe
+run_start
+run_describe_start: ROOT_DESCRIBE_BLOCK
+run_describe_start: describe
+test_start: receives events
+test_fn_start: receives events
+called true
+test_fn_failure: receives events
+test_done: receives events
+run_describe_finish: describe
+run_describe_finish: ROOT_DESCRIBE_BLOCK
+run_finish
+
+unhandledErrors: 0
+`;
+
+exports[`removeEventHandler unregisters a callback from events 1`] = `
+start_describe_definition: describe
+add_test: does not receive events
+finish_describe_definition: describe
+run_start
+run_describe_start: ROOT_DESCRIBE_BLOCK
+run_describe_start: describe
+test_start: does not receive events
+test_fn_start: does not receive events
+called false
+test_fn_failure: does not receive events
+test_done: does not receive events
+run_describe_finish: describe
+run_describe_finish: ROOT_DESCRIBE_BLOCK
+run_finish
+
+unhandledErrors: 0
+`;

packages/jest-circus/src/__tests__/eventHandler.test.ts

@@ -0,0 +1,44 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. 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.
+ */
+
+import wrap from 'jest-snapshot-serializer-raw';
+import {runTest} from '../__mocks__/testUtils';
+
+test('addEventHandler registers a callback with events', () => {
+  const {stdout} = runTest(`
+    let called = false;
+    const callback = () => called = true;
+    addEventHandler(callback);
+
+    describe('describe', () => {
+      test('receives events', () => {
+        console.log('called', called);
+        expect(called).toEqual(true);
+      })
+    });
+  `);
+
+  expect(wrap(stdout)).toMatchSnapshot();
+});
+
+test('removeEventHandler unregisters a callback from events', () => {
+  const {stdout} = runTest(`
+    let called = false;
+    const callback = () => called = true;
+    addEventHandler(callback);
+    removeEventHandler(callback);
+
+    describe('describe', () => {
+      test('does not receive events', () => {
+        console.log('called', called);
+        expect(called).toEqual(false);
+      })
+    });
+  `);
+
+  expect(wrap(stdout)).toMatchSnapshot();
+});

packages/jest-circus/src/index.ts

@@ -10,7 +10,13 @@ import {bind as bindEach} from 'jest-each';
 import {ErrorWithStack, isPromise} from 'jest-util';
 import {dispatchSync} from './state';
 
-export {setState, getState, resetState} from './state';
+export {
+  setState,
+  getState,
+  resetState,
+  addEventHandler,
+  removeEventHandler,
+} from './state';
 export {default as run} from './run';
 
 type THook = (fn: Circus.HookFn, timeout?: number) => void;

packages/jest-circus/src/state.ts

@@ -8,10 +8,10 @@
 import type {Circus} from '@jest/types';
 import eventHandler from './eventHandler';
 import formatNodeAssertErrors from './formatNodeAssertErrors';
-import {STATE_SYM} from './types';
+import {EVENT_HANDLERS, STATE_SYM} from './types';
 import {makeDescribe} from './utils';
 
-const eventHandlers: Array<Circus.EventHandler> = [
+global[EVENT_HANDLERS] = global[EVENT_HANDLERS] || [
   eventHandler,
   formatNodeAssertErrors,
 ];
@@ -46,17 +46,24 @@ export const setState = (state: Circus.State): Circus.State =>
   (global[STATE_SYM] = state);
 
 export const dispatch = async (event: Circus.AsyncEvent): Promise<void> => {
-  for (const handler of eventHandlers) {
+  for (const handler of global[EVENT_HANDLERS]) {
     await handler(event, getState());
   }
 };
 
 export const dispatchSync = (event: Circus.SyncEvent): void => {
-  for (const handler of eventHandlers) {
+  for (const handler of global[EVENT_HANDLERS]) {
     handler(event, getState());
   }
 };
 
 export const addEventHandler = (handler: Circus.EventHandler): void => {
-  eventHandlers.push(handler);
+  global[EVENT_HANDLERS].push(handler);
+};
+
+export const removeEventHandler = (handler: Circus.EventHandler): void => {
+  const index = global[EVENT_HANDLERS].lastIndexOf(handler);
+  if (index !== -1) {
+    global[EVENT_HANDLERS].splice(index, 1);
+  }
 };

packages/jest-circus/src/types.ts

@@ -19,13 +19,17 @@ export const RETRY_TIMES = Symbol.for(
 export const TEST_TIMEOUT_SYMBOL = Symbol.for(
   'TEST_TIMEOUT_SYMBOL',
 ) as unknown as 'TEST_TIMEOUT_SYMBOL';
+export const EVENT_HANDLERS = Symbol.for(
+  'EVENT_HANDLERS',
+) as unknown as 'EVENT_HANDLERS';
 
 declare global {
   module NodeJS {
     interface Global {
       STATE_SYM_SYMBOL: Circus.State;
       RETRY_TIMES_SYMBOL: string;
       TEST_TIMEOUT_SYMBOL: number;
+      EVENT_HANDLERS: Array<Circus.EventHandler>;
       expect: typeof expect;
     }
   }