feat(jest-runtime): expose isEnvironmentTornDown variable

CHANGELOG.md

@@ -8,6 +8,7 @@
 - `[jest-haste-map]` ignore Sapling vcs directories (`.sl/`) ([#13674](https://github.com/facebook/jest/pull/13674))
 - `[jest-resolve]` Support subpath imports ([#13705](https://github.com/facebook/jest/pull/13705), [#13723](https://github.com/facebook/jest/pull/13723))
 - `[jest-runtime]` Add `jest.isolateModulesAsync` for scoped module initialization of asynchronous functions ([#13680](https://github.com/facebook/jest/pull/13680))
+- `[jest-runtime]` Add `jest.isEnvironmentTornDown` function ([#13698](https://github.com/facebook/jest/pull/13698))
 - `[jest-test-result]` Added `skipped` and `focused` status to `FormattedTestResult` ([#13700](https://github.com/facebook/jest/pull/13700))
 
 ### Fixes

packages/jest-environment/src/index.ts

@@ -172,6 +172,15 @@ export interface Jest {
    * local module state doesn't conflict between tests.
    */
   isolateModules(fn: () => void): Jest;
+  /**
+   * Returns `true` if test environment has been torn down.
+   * @example
+   * if (jest.isEnvironmentTornDown()) {
+   *   // The Jest environment has been torn down, so stop doing work
+   *   return;
+   * }
+   */
+  isEnvironmentTornDown(): boolean;
   /**
    * `jest.isolateModulesAsync()` is the equivalent of `jest.isolateModules()`, but for
    * async functions to be wrapped. The caller is expected to `await` the completion of

packages/jest-runtime/src/__tests__/runtime_jest_fn.js

@@ -66,4 +66,21 @@ describe('Runtime', () => {
       expect(mock2).not.toHaveBeenCalled();
     });
   });
+
+  describe('jest.isEnvironmentTornDown()', () => {
+    it('should be set to false when the environment is not torn down', async () => {
+      const runtime = await createRuntime(__filename);
+      const root = runtime.requireModule(runtime.__mockRootPath);
+      runtime['isTornDown'] = false;
+      expect(root.jest.isEnvironmentTornDown()).toBe(false);
+    });
+
+    it('should be set to true when the environment is torn down', async () => {
+      const runtime = await createRuntime(__filename);
+      const root = runtime.requireModule(runtime.__mockRootPath);
+      expect(root.jest.isEnvironmentTornDown()).toBe(false);
+      runtime.teardown();
+      expect(root.jest.isEnvironmentTornDown()).toBe(true);
+    });
+  });
 });

packages/jest-runtime/src/index.ts

@@ -2237,6 +2237,7 @@ export default class Runtime {
         return this._globalConfig.seed;
       },
       getTimerCount: () => _getFakeTimers().getTimerCount(),
+      isEnvironmentTornDown: () => this.isTornDown,
       isMockFunction: this._moduleMocker.isMockFunction,
       isolateModules,
       isolateModulesAsync: this.isolateModulesAsync,

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

@@ -587,3 +587,6 @@ expectError(jest.setTimeout());
 
 expectType<number>(jest.getSeed());
 expectError(jest.getSeed(123));
+
+expectType<boolean>(jest.isEnvironmentTornDown());
+expectError<boolean>(jest.isEnvironmentTornDown(123));