fix: jest-circus shares events among imports #11483

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

@@ -36,7 +36,7 @@ export const runTest = (
     global.afterAll = circus.afterAll;
 
     const testEventHandler = require('${TEST_EVENT_HANDLER_PATH}').default;
-    const {addEventHandler, getState} = require('${CIRCUS_STATE_PATH}');
+    const {addEventHandler, removeEventHandler, getState} = require('${CIRCUS_STATE_PATH}');
     getState().randomize = ${opts?.randomize};
     getState().seed = ${opts?.seed ?? 0};
     addEventHandler(testEventHandler);

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

@@ -0,0 +1,25 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * 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: any = 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, convertDescriptorToString, 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

@@ -8,13 +8,16 @@
 import type {Circus, Global} 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> = [
-  eventHandler,
-  formatNodeAssertErrors,
-];
+/* eslint-disable no-restricted-globals */
+const handlers: Array<Circus.EventHandler> = ((global as Global.Global)[
+  EVENT_HANDLERS
+] = ((global as Global.Global)[
+  EVENT_HANDLERS
+] as Array<Circus.EventHandler>) || [eventHandler, formatNodeAssertErrors]);
+/* eslint-enable */
 
 export const ROOT_DESCRIBE_BLOCK_NAME = 'ROOT_DESCRIBE_BLOCK';
 
@@ -52,17 +55,24 @@ export const setState = (state: Circus.State): Circus.State =>
 /* eslint-enable */
 
 export const dispatch = async (event: Circus.AsyncEvent): Promise<void> => {
-  for (const handler of eventHandlers) {
+  for (const handler of handlers) {
     await handler(event, getState());
   }
 };
 
 export const dispatchSync = (event: Circus.SyncEvent): void => {
-  for (const handler of eventHandlers) {
+  for (const handler of handlers) {
     handler(event, getState());
   }
 };
 
 export const addEventHandler = (handler: Circus.EventHandler): void => {
-  eventHandlers.push(handler);
+  handlers.push(handler);
+};
+
+export const removeEventHandler = (handler: Circus.EventHandler): void => {
+  const index = handlers.lastIndexOf(handler);
+  if (index !== -1) {
+    handlers.splice(index, 1);
+  }
 };

packages/jest-circus/src/types.ts

@@ -11,4 +11,5 @@ export const RETRY_IMMEDIATELY = Symbol.for('RETRY_IMMEDIATELY');
 export const WAIT_BEFORE_RETRY = Symbol.for('WAIT_BEFORE_RETRY');
 // To pass this value from Runtime object to state we need to use global[sym]
 export const TEST_TIMEOUT_SYMBOL = Symbol.for('TEST_TIMEOUT_SYMBOL');
+export const EVENT_HANDLERS = Symbol.for('EVENT_HANDLERS');
 export const LOG_ERRORS_BEFORE_RETRY = Symbol.for('LOG_ERRORS_BEFORE_RETRY');