Bind to Circus events via an optional event handler on any custom env.

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### Features
 
+- `[jest-circus]` Bind to Circus events via an optional event handler on any custom env ([#8344](https://github.com/facebook/jest/pull/8344)
 - `[expect]` Improve report when matcher fails, part 15 ([#8281](https://github.com/facebook/jest/pull/8281))
 - `[jest-cli]` Update `--forceExit` and "did not exit for one second" message colors ([#8329](https://github.com/facebook/jest/pull/8329))
 - `[expect]` Improve report when matcher fails, part 16 ([#8306](https://github.com/facebook/jest/pull/8306))

docs/Configuration.md

@@ -861,6 +861,8 @@ test('use jsdom in this test file', () => {
 
 You can create your own module that will be used for setting up the test environment. The module must export a class with `setup`, `teardown` and `runScript` methods. You can also pass variables from this module to your test suites by assigning them to `this.global` object – this will make them available in your test suites as global variables.
 
+The class may optionally expose a `handleTestEvent` method to bind to events fired by [`jest-circus`](https://github.com/facebook/jest/tree/master/packages/jest-circus).
+
 Any docblock pragmas in test files will be passed to the environment constructor and can be used for per-test configuration. If the pragma does not have a value, it will be present in the object with it's value set to an empty string. If the pragma is not present, it will not be present in the object.
 
 _Note: TestEnvironment is sandboxed. Each test suite will trigger setup/teardown in their own TestEnvironment._
@@ -898,6 +900,12 @@ class CustomEnvironment extends NodeEnvironment {
   runScript(script) {
     return super.runScript(script);
   }
+
+  handleTestEvent(event, state) {
+    if (event.name === 'test_start') {
+      // ...
+    }
+  }
 }
 
 module.exports = CustomEnvironment;

e2e/__tests__/testEnvironmentCircus.test.ts

@@ -0,0 +1,46 @@
+/**
+ * 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 {skipSuiteOnJasmine} from '@jest/test-utils';
+import runJest from '../runJest';
+
+skipSuiteOnJasmine();
+
+it('calls testEnvironment handleTestEvent', () => {
+  const result = runJest('test-environment-circus');
+  expect(result.failed).toEqual(false);
+  expect(result.stdout.split('\n')).toMatchInlineSnapshot(`
+    Array [
+      "setup",
+      "add_hook",
+      "add_hook",
+      "add_test",
+      "add_test",
+      "run_start",
+      "run_describe_start",
+      "test_start: test name here",
+      "hook_start",
+      "hook_success: test name here",
+      "hook_start",
+      "hook_success: test name here",
+      "test_fn_start: test name here",
+      "test_fn_success: test name here",
+      "test_done: test name here",
+      "test_start: second test name here",
+      "hook_start",
+      "hook_success: second test name here",
+      "hook_start",
+      "hook_success: second test name here",
+      "test_fn_start: second test name here",
+      "test_fn_success: second test name here",
+      "test_done: second test name here",
+      "run_describe_finish",
+      "run_finish",
+      "teardown",
+    ]
+  `);
+});

e2e/test-environment-circus/CircusHandleTestEventEnvironment.js

@@ -0,0 +1,13 @@
+// Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+
+'use strict';
+
+const JSDOMEnvironment = require('jest-environment-jsdom');
+
+class TestEnvironment extends JSDOMEnvironment {
+  handleTestEvent(event) {
+    console.log(event.name + (event.test ? ': ' + event.test.name : ''));
+  }
+}
+
+module.exports = TestEnvironment;

e2e/test-environment-circus/__tests__/circusHandleTestEvent.test.js

@@ -0,0 +1,15 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * @jest-environment ./CircusHandleTestEventEnvironment.js
+ */
+
+beforeEach(() => {});
+
+test('test name here', () => {
+  expect(true).toBe(true);
+});
+
+test('second test name here', () => {
+  expect(true).toBe(true);
+});

e2e/test-environment-circus/package.json

@@ -0,0 +1,5 @@
+{
+  "jest": {
+    "testEnvironment": "node"
+  }
+}

packages/jest-circus/README.md

@@ -9,6 +9,25 @@
 
 Circus is a flux-based test runner for Jest that is fast, easy to maintain, and simple to extend.
 
+Circus allows you to bind to events via an optional event handler on any [custom environment](https://jestjs.io/docs/en/configuration#testenvironment-string). See the [type definitions](https://github.com/facebook/jest/blob/master/packages/jest-circus/src/types.ts) for more information on the events and state data currently available.
+
+```js
+import {NodeEnvironment} from 'jest-environment-node';
+import {Event, State} from 'jest-circus';
+
+class MyCustomEnvironment extends NodeEnvironment {
+  //...
+
+  handleTestEvent(event: Event, state: State) {
+    if (event.name === 'test_start') {
+      // ...
+    }
+  }
+}
+```
+
+Mutating event or state data is currently unsupported and may cause unexpected behavior or break in a future release without warning. New events, event data, and/or state data will not be considered a breaking change and may be added in any minor release.
+
 ## Installation
 
 Install `jest-circus` using yarn:

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

@@ -6,9 +6,9 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  */
 
-import {EventHandler} from '../types';
+import {Circus} from '@jest/types';
 
-const testEventHandler: EventHandler = (event, state) => {
+const testEventHandler: Circus.EventHandler = (event, state) => {
   switch (event.name) {
     case 'start_describe_definition':
     case 'finish_describe_definition': {

packages/jest-circus/src/eventHandler.ts

@@ -5,7 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {EventHandler, TEST_TIMEOUT_SYMBOL} from './types';
+import {Circus} from '@jest/types';
+import {TEST_TIMEOUT_SYMBOL} from './types';
 
 import {
   addErrorToEachTestUnderDescribe,
@@ -20,7 +21,7 @@ import {
   restoreGlobalErrorHandlers,
 } from './globalErrorHandlers';
 
-const eventHandler: EventHandler = (event, state): void => {
+const eventHandler: Circus.EventHandler = (event, state): void => {
   switch (event.name) {
     case 'include_test_location_in_result': {
       state.includeTestLocationInResult = true;

packages/jest-circus/src/formatNodeAssertErrors.ts

@@ -6,6 +6,7 @@
  */
 
 import {AssertionError} from 'assert';
+import {Circus} from '@jest/types';
 import {
   diff,
   printExpected,
@@ -14,7 +15,6 @@ import {
 } from 'jest-matcher-utils';
 import chalk from 'chalk';
 import prettyFormat from 'pretty-format';
-import {Event, State, TestError} from './types';
 
 interface AssertionErrorWithStack extends AssertionError {
   stack: string;
@@ -38,10 +38,10 @@ const humanReadableOperators: {[key: string]: string} = {
   strictEqual: 'to strictly be equal',
 };
 
-const formatNodeAssertErrors = (event: Event, state: State) => {
+const formatNodeAssertErrors = (event: Circus.Event, state: Circus.State) => {
   switch (event.name) {
     case 'test_done': {
-      event.test.errors = event.test.errors.map((errors: TestError) => {
+      event.test.errors = event.test.errors.map((errors: Circus.TestError) => {
         let error;
         if (Array.isArray(errors)) {
           const [originalError, asyncError] = errors;

packages/jest-circus/src/globalErrorHandlers.ts

@@ -5,8 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import {Circus} from '@jest/types';
 import {dispatch} from './state';
-import {GlobalErrorHandlers} from './types';
 
 const uncaught: NodeJS.UncaughtExceptionListener &
   NodeJS.UnhandledRejectionListener = (error: unknown) => {
@@ -15,7 +15,7 @@ const uncaught: NodeJS.UncaughtExceptionListener &
 
 export const injectGlobalErrorHandlers = (
   parentProcess: NodeJS.Process,
-): GlobalErrorHandlers => {
+): Circus.GlobalErrorHandlers => {
   const uncaughtException = process.listeners('uncaughtException').slice();
   const unhandledRejection = process.listeners('unhandledRejection').slice();
   parentProcess.removeAllListeners('uncaughtException');
@@ -27,7 +27,7 @@ export const injectGlobalErrorHandlers = (
 
 export const restoreGlobalErrorHandlers = (
   parentProcess: NodeJS.Process,
-  originalErrorHandlers: GlobalErrorHandlers,
+  originalErrorHandlers: Circus.GlobalErrorHandlers,
 ) => {
   parentProcess.removeListener('uncaughtException', uncaught);
   parentProcess.removeListener('unhandledRejection', uncaught);

packages/jest-circus/src/index.ts

@@ -9,28 +9,21 @@ import chalk from 'chalk';
 import {bind as bindEach} from 'jest-each';
 import {formatExecError} from 'jest-message-util';
 import {ErrorWithStack, isPromise} from 'jest-util';
-import {Global} from '@jest/types';
-import {
-  BlockFn,
-  HookFn,
-  HookType,
-  TestFn,
-  BlockMode,
-  BlockName,
-  TestName,
-  TestMode,
-} from './types';
+import {Circus, Global} from '@jest/types';
 import {dispatch} from './state';
 
-type THook = (fn: HookFn, timeout?: number) => void;
-type DescribeFn = (blockName: BlockName, blockFn: BlockFn) => void;
+type THook = (fn: Circus.HookFn, timeout?: number) => void;
+type DescribeFn = (
+  blockName: Circus.BlockName,
+  blockFn: Circus.BlockFn,
+) => void;
 
 const describe = (() => {
-  const describe = (blockName: BlockName, blockFn: BlockFn) =>
+  const describe = (blockName: Circus.BlockName, blockFn: Circus.BlockFn) =>
     _dispatchDescribe(blockFn, blockName, describe);
-  const only = (blockName: BlockName, blockFn: BlockFn) =>
+  const only = (blockName: Circus.BlockName, blockFn: Circus.BlockFn) =>
     _dispatchDescribe(blockFn, blockName, only, 'only');
-  const skip = (blockName: BlockName, blockFn: BlockFn) =>
+  const skip = (blockName: Circus.BlockName, blockFn: Circus.BlockFn) =>
     _dispatchDescribe(blockFn, blockName, skip, 'skip');
 
   describe.each = bindEach(describe, false);
@@ -45,10 +38,10 @@ const describe = (() => {
 })();
 
 const _dispatchDescribe = (
-  blockFn: BlockFn,
-  blockName: BlockName,
+  blockFn: Circus.BlockFn,
+  blockName: Circus.BlockName,
   describeFn: DescribeFn,
-  mode?: BlockMode,
+  mode?: Circus.BlockMode,
 ) => {
   const asyncError = new ErrorWithStack(undefined, describeFn);
   if (blockFn === undefined) {
@@ -102,8 +95,8 @@ const _dispatchDescribe = (
 };
 
 const _addHook = (
-  fn: HookFn,
-  hookType: HookType,
+  fn: Circus.HookFn,
+  hookType: Circus.HookType,
   hookFn: THook,
   timeout?: number,
 ) => {
@@ -130,14 +123,23 @@ const afterAll: THook = (fn, timeout) =>
   _addHook(fn, 'afterAll', afterAll, timeout);
 
 const test: Global.It = (() => {
-  const test = (testName: TestName, fn: TestFn, timeout?: number): void =>
-    _addTest(testName, undefined, fn, test, timeout);
-  const skip = (testName: TestName, fn?: TestFn, timeout?: number): void =>
-    _addTest(testName, 'skip', fn, skip, timeout);
-  const only = (testName: TestName, fn: TestFn, timeout?: number): void =>
-    _addTest(testName, 'only', fn, test.only, timeout);
-
-  test.todo = (testName: TestName, ...rest: Array<any>): void => {
+  const test = (
+    testName: Circus.TestName,
+    fn: Circus.TestFn,
+    timeout?: number,
+  ): void => _addTest(testName, undefined, fn, test, timeout);
+  const skip = (
+    testName: Circus.TestName,
+    fn?: Circus.TestFn,
+    timeout?: number,
+  ): void => _addTest(testName, 'skip', fn, skip, timeout);
+  const only = (
+    testName: Circus.TestName,
+    fn: Circus.TestFn,
+    timeout?: number,
+  ): void => _addTest(testName, 'only', fn, test.only, timeout);
+
+  test.todo = (testName: Circus.TestName, ...rest: Array<any>): void => {
     if (rest.length > 0 || typeof testName !== 'string') {
       throw new ErrorWithStack(
         'Todo must be called with only a description.',
@@ -148,10 +150,14 @@ const test: Global.It = (() => {
   };
 
   const _addTest = (
-    testName: TestName,
-    mode: TestMode,
-    fn: TestFn | undefined,
-    testFn: (testName: TestName, fn: TestFn, timeout?: number) => void,
+    testName: Circus.TestName,
+    mode: Circus.TestMode,
+    fn: Circus.TestFn | undefined,
+    testFn: (
+      testName: Circus.TestName,
+      fn: Circus.TestFn,
+      timeout?: number,
+    ) => void,
     timeout?: number,
   ) => {
     const asyncError = new ErrorWithStack(undefined, testFn);
@@ -195,7 +201,10 @@ const test: Global.It = (() => {
 
 const it: Global.It = test;
 
-export = {
+export type Event = Circus.Event;
+export type State = Circus.State;
+export {afterAll, afterEach, beforeAll, beforeEach, describe, it, test};
+export default {
   afterAll,
   afterEach,
   beforeAll,

packages/jest-circus/src/legacy-code-todo-rewrite/jestAdapter.ts

@@ -39,6 +39,7 @@ const jestAdapter = async (
 
   const {globals, snapshotState} = initialize({
     config,
+    environment,
     getBabelTraverse,
     getPrettier,
     globalConfig,