feat(jest-runner): improve typings by exposing TestRunner abstract classes

packages/jest-runner/__typetests__/jest-runner.test.ts

@@ -0,0 +1,63 @@
+/**
+ * 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 type {UnsubscribeFn} from 'emittery';
+import {expectType} from 'tsd-lite';
+import type {Test, TestEvents} from '@jest/test-result';
+import type {Config} from '@jest/types';
+import {CallbackTestRunner, EmittingTestRunner} from 'jest-runner';
+import type {
+  OnTestFailure,
+  OnTestStart,
+  OnTestSuccess,
+  TestRunnerContext,
+  TestRunnerOptions,
+  TestWatcher,
+} from 'jest-runner';
+
+const globalConfig = {} as Config.GlobalConfig;
+const runnerContext = {} as TestRunnerContext;
+
+class CallbackRunner extends CallbackTestRunner {
+  override async runTests(
+    tests: Array<Test>,
+    watcher: TestWatcher,
+    onStart: OnTestStart,
+    onResult: OnTestSuccess,
+    onFailure: OnTestFailure,
+    options: TestRunnerOptions,
+  ): Promise<void> {
+    return;
+  }
+}
+
+const callbackRunner = new CallbackRunner(globalConfig, runnerContext);
+
+expectType<boolean | undefined>(callbackRunner.isSerial);
+expectType<false>(callbackRunner.supportsEventEmitters);
+
+class EmittingRunner extends EmittingTestRunner {
+  override on<Name extends keyof TestEvents>(
+    eventName: string,
+    listener: (eventData: TestEvents[Name]) => void | Promise<void>,
+  ): UnsubscribeFn {
+    return () => {};
+  }
+
+  override async runTests(
+    tests: Array<Test>,
+    watcher: TestWatcher,
+    options: TestRunnerOptions,
+  ): Promise<void> {
+    return;
+  }
+}
+
+const emittingRunner = new EmittingRunner(globalConfig, runnerContext);
+
+expectType<boolean | undefined>(emittingRunner.isSerial);
+expectType<true>(emittingRunner.supportsEventEmitters);

packages/jest-runner/__typetests__/tsconfig.json

@@ -0,0 +1,11 @@
+{
+  "extends": "../../../tsconfig.json",
+  "compilerOptions": {
+    "noUnusedLocals": false,
+    "noUnusedParameters": false,
+    "skipLibCheck": true,
+
+    "types": []
+  },
+  "include": ["./**/*"]
+}

packages/jest-runner/package.json

@@ -39,10 +39,11 @@
     "throat": "^6.0.1"
   },
   "devDependencies": {
+    "@tsd/typescript": "~4.6.2",
     "@types/exit": "^0.1.30",
     "@types/graceful-fs": "^4.1.2",
     "@types/source-map-support": "^0.5.0",
-    "jest-jasmine2": "^28.0.0-alpha.8"
+    "tsd-lite": "^0.5.1"
   },
   "engines": {
     "node": "^12.13.0 || ^14.15.0 || ^16.13.0 || >=17.0.0"

packages/jest-runner/src/index.ts

@@ -26,16 +26,15 @@ interface WorkerInterface extends Worker {
   worker: typeof worker;
 }
 
+export {CallbackTestRunner, EmittingTestRunner} from './types';
 export type {
   OnTestFailure,
   OnTestStart,
   OnTestSuccess,
   TestWatcher,
   TestRunnerContext,
   TestRunnerOptions,
-  EmittingTestRunner,
   JestTestRunner,
-  TestRunner,
 } from './types';
 
 export default class TestRunner extends EmittingTestRunner {

packages/jest-runner/src/types.ts

@@ -74,7 +74,7 @@ abstract class BaseTestRunner {
   ) {}
 }
 
-export abstract class TestRunner extends BaseTestRunner {
+export abstract class CallbackTestRunner extends BaseTestRunner {
   readonly supportsEventEmitters = false;
 
   abstract runTests(
@@ -102,4 +102,4 @@ export abstract class EmittingTestRunner extends BaseTestRunner {
   ): Emittery.UnsubscribeFn;
 }
 
-export type JestTestRunner = TestRunner | EmittingTestRunner;
+export type JestTestRunner = CallbackTestRunner | EmittingTestRunner;

yarn.lock

@@ -13309,7 +13309,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"jest-jasmine2@^28.0.0-alpha.8, jest-jasmine2@workspace:packages/jest-jasmine2":
+"jest-jasmine2@workspace:packages/jest-jasmine2":
   version: 0.0.0-use.local
   resolution: "jest-jasmine2@workspace:packages/jest-jasmine2"
   dependencies:
@@ -13542,6 +13542,7 @@ __metadata:
     "@jest/test-result": ^28.0.0-alpha.8
     "@jest/transform": ^28.0.0-alpha.8
     "@jest/types": ^28.0.0-alpha.8
+    "@tsd/typescript": ~4.6.2
     "@types/exit": ^0.1.30
     "@types/graceful-fs": ^4.1.2
     "@types/node": "*"
@@ -13552,7 +13553,6 @@ __metadata:
     jest-docblock: ^28.0.0-alpha.6
     jest-environment-node: ^28.0.0-alpha.8
     jest-haste-map: ^28.0.0-alpha.8
-    jest-jasmine2: ^28.0.0-alpha.8
     jest-leak-detector: ^28.0.0-alpha.8
     jest-message-util: ^28.0.0-alpha.8
     jest-resolve: ^28.0.0-alpha.8
@@ -13561,6 +13561,7 @@ __metadata:
     jest-worker: ^28.0.0-alpha.8
     source-map-support: ^0.5.6
     throat: ^6.0.1
+    tsd-lite: ^0.5.1
   languageName: unknown
   linkType: soft