fix: jest-circus shares events among imports #11483

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 ### Fixes
 
+- `[jest-circus]` Shares events with event handlers among imports ([#11483](https://github.com/facebook/jest/pull/11483))
 - `[expect]` Tweak and improve types ([#11949](https://github.com/facebook/jest/pull/11949))
 - `[jest-runtime]` Ensure absolute paths can be resolved within test modules ([#11943](https://github.com/facebook/jest/pull/11943))
 - `[jest-runtime]` Fix `instanceof` for `ModernFakeTimers` and `LegacyFakeTimers` methods ([#11946](https://github.com/facebook/jest/pull/11946))

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__/eventHandler.test.ts

@@ -0,0 +1,25 @@
+/**
+ * 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.
+ */
+
+// addEventHandler and removeEventHandler are provided in the ./index
+import {addEventHandler, removeEventHandler} from '../index';
+// dispatch comes from the ./state
+import {dispatch} from '../state';
+
+test('addEventHandler and removeEventHandler control handlers', async () => {
+  const spy = jest.fn();
+
+  addEventHandler(spy);
+  expect(spy).not.toHaveBeenCalledWith({name: 'unknown1'}, expect.anything());
+  await dispatch({name: 'unknown1' as any});
+  expect(spy).toHaveBeenCalledWith({name: 'unknown1'}, expect.anything());
+
+  removeEventHandler(spy);
+  expect(spy).not.toHaveBeenCalledWith({name: 'unknown2'}, expect.anything());
+  await dispatch({name: 'unknown2' as any});
+  expect(spy).not.toHaveBeenCalledWith({name: 'unknown2'}, expect.anything());
+});

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;
     }
   }