jest/e2e/__tests__/runtimeInternalModuleRegistry.test.ts

/**
 * 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.
 */

import {json as runWithJson} from '../runJest';

describe('Runtime Internal Module Registry', () => {
  // Previously, if Jest required a module (e.g. requiring `mkdirp` from
  // `jest-util`) and the project *using* Jest also required that module, Jest
  // wouldn't re-require it and thus ignored any mocks that the module may have
  // used.
  //
  // This test verifies that behavior doesn't happen anymore, and correctly
  // uses two module registries: an internal registry that's used specifically by
  // Jest to require any internal modules used when setting up the test
  // environment, and a "normal" module registry that's used by the actual test
  // code (and can safely be cleared after every test)
  it('correctly makes use of internal module registry when requiring modules', () => {
    const {json} = runWithJson('runtime-internal-module-registry', []);

    expect(json.numTotalTests).toBe(1);
    expect(json.numPassedTests).toBe(1);
  });
});