private _requireResolve(
    from: Config.Path,
    moduleName?: string,
    options: ResolveOptions = {},
  ) {
    if (moduleName == null) {
      throw new Error(
        'The first argument to require.resolve must be a string. Received null or undefined.',
      );
    }

    const {paths} = options;

    if (paths) {
      for (const p of paths) {
        const absolutePath = path.resolve(from, '..', p);
        const module = this._resolver.resolveModuleFromDirIfExists(
          absolutePath,
          moduleName,
          // required to also resolve files without leading './' directly in the path
          {paths: [absolutePath]},
        );
        if (module) {
          return module;
        }
      }
      throw new Error(
        `Cannot resolve module '${moduleName}' from paths ['${paths.join(
          "', '",
        )}'] from ${from}`,
      );
    }
    try {
      return this._resolveModule(from, moduleName);
    } catch (err) {
      const module = this._resolver.getMockModule(from, moduleName);

      if (module) {
        return module;
      } else {
        throw err;
      }
    }
  }

    return dependencies.reduce<Array<Config.Path>>((acc, dependency) => {
      if (this._resolver.isCoreModule(dependency)) {
        return acc;
      }
      let resolvedDependency;
      try {
        resolvedDependency = this._resolver.resolveModule(
          file,
          dependency,
          options,
        );
      } catch (e) {
        resolvedDependency = this._resolver.getMockModule(file, dependency);
      }

      if (resolvedDependency) {
        acc.push(resolvedDependency);
      }

      return acc;
    }, []);

  private _shouldMock(from: Config.Path, moduleName: string) {
    const mockPath = this._resolver.getModulePath(from, moduleName);
    if (mockPath in this._virtualMocks) {
      return true;
    }

    const explicitShouldMock = this._explicitShouldMock;
    const moduleID = this._resolver.getModuleID(
      this._virtualMocks,
      from,
      moduleName,
    );
    const key = from + path.delimiter + moduleID;

    if (moduleID in explicitShouldMock) {
      return explicitShouldMock[moduleID];
    }

    if (
      !this._shouldAutoMock ||
      this._resolver.isCoreModule(moduleName) ||
      this._shouldUnmockTransitiveDependenciesCache[key]
    ) {
      return false;
    }

    if (moduleID in this._shouldMockModuleCache) {
      return this._shouldMockModuleCache[moduleID];
    }

    let modulePath;
    try {
      modulePath = this._resolveModule(from, moduleName);
    } catch (e) {
      const manualMock = this._resolver.getMockModule(from, moduleName);
      if (manualMock) {
        this._shouldMockModuleCache[moduleID] = true;
        return true;
      }
      throw e;
    }

    if (this._unmockList && this._unmockList.test(modulePath)) {
      this._shouldMockModuleCache[moduleID] = false;
      return false;
    }

    // transitive unmocking for package managers that store flat packages (npm3)
    const currentModuleID = this._resolver.getModuleID(
      this._virtualMocks,
      from,
    );
    if (
      this._transitiveShouldMock[currentModuleID] === false ||
      (from.includes(NODE_MODULES) &&
        modulePath.includes(NODE_MODULES) &&
        ((this._unmockList && this._unmockList.test(from)) ||
          explicitShouldMock[currentModuleID] === false))
    ) {
      this._transitiveShouldMock[moduleID] = false;
      this._shouldUnmockTransitiveDependenciesCache[key] = true;
      return false;
    }

    return (this._shouldMockModuleCache[moduleID] = true);
  }

  requireMock(from: Config.Path, moduleName: string) {
    const moduleID = this._resolver.getModuleID(
      this._virtualMocks,
      from,
      moduleName,
    );

    if (this._isolatedMockRegistry && this._isolatedMockRegistry[moduleID]) {
      return this._isolatedMockRegistry[moduleID];
    } else if (this._mockRegistry[moduleID]) {
      return this._mockRegistry[moduleID];
    }

    const mockRegistry = this._isolatedMockRegistry || this._mockRegistry;

    if (moduleID in this._mockFactories) {
      return (mockRegistry[moduleID] = this._mockFactories[moduleID]());
    }

    const manualMockOrStub = this._resolver.getMockModule(from, moduleName);
    let modulePath;
    if (manualMockOrStub) {
      modulePath = this._resolveModule(from, manualMockOrStub);
    } else {
      modulePath = this._resolveModule(from, moduleName);
    }

    let isManualMock =
      manualMockOrStub &&
      !this._resolver.resolveStubModuleName(from, moduleName);
    if (!isManualMock) {
      // If the actual module file has a __mocks__ dir sitting immediately next
      // to it, look to see if there is a manual mock for this file.
      //
      // subDir1/my_module.js
      // subDir1/__mocks__/my_module.js
      // subDir2/my_module.js
      // subDir2/__mocks__/my_module.js
      //
      // Where some other module does a relative require into each of the
      // respective subDir{1,2} directories and expects a manual mock
      // corresponding to that particular my_module.js file.

      const moduleDir = path.dirname(modulePath);
      const moduleFileName = path.basename(modulePath);
      const potentialManualMock = path.join(
        moduleDir,
        '__mocks__',
        moduleFileName,
      );
      if (fs.existsSync(potentialManualMock)) {
        isManualMock = true;
        modulePath = potentialManualMock;
      }
    }
    if (isManualMock) {
      const localModule: InitialModule = {
        children: [],
        exports: {},
        filename: modulePath,
        id: modulePath,
        loaded: false,
      };

      // Only include the fromPath if a moduleName is given. Else treat as root.
      const fromPath = moduleName ? from : null;
      this._execModule(localModule, undefined, mockRegistry, fromPath);
      mockRegistry[moduleID] = localModule.exports;
      localModule.loaded = true;
    } else {
      // Look for a real module to generate an automock from
      mockRegistry[moduleID] = this._generateMock(from, moduleName);
    }

    return mockRegistry[moduleID];
  }

  requireModule(
    from: Config.Path,
    moduleName?: string,
    options?: InternalModuleOptions,
    isRequireActual?: boolean | null,
  ) {
    const moduleID = this._resolver.getModuleID(
      this._virtualMocks,
      from,
      moduleName,
    );
    let modulePath;

    // Some old tests rely on this mocking behavior. Ideally we'll change this
    // to be more explicit.
    const moduleResource = moduleName && this._resolver.getModule(moduleName);
    const manualMock =
      moduleName && this._resolver.getMockModule(from, moduleName);
    if (
      (!options || !options.isInternalModule) &&
      !isRequireActual &&
      !moduleResource &&
      manualMock &&
      manualMock !== this._isCurrentlyExecutingManualMock &&
      this._explicitShouldMock[moduleID] !== false
    ) {
      modulePath = manualMock;
    }

    if (moduleName && this._resolver.isCoreModule(moduleName)) {
      return this._requireCoreModule(moduleName);
    }

    if (!modulePath) {
      modulePath = this._resolveModule(from, moduleName);
    }

    let moduleRegistry;

    if (!options || !options.isInternalModule) {
      if (this._moduleRegistry[modulePath] || !this._isolatedModuleRegistry) {
        moduleRegistry = this._moduleRegistry;
      } else {
        moduleRegistry = this._isolatedModuleRegistry;
      }
    } else {
      moduleRegistry = this._internalModuleRegistry;
    }

    if (!moduleRegistry[modulePath]) {
      // We must register the pre-allocated module object first so that any
      // circular dependencies that may arise while evaluating the module can
      // be satisfied.
      const localModule: InitialModule = {
        children: [],
        exports: {},
        filename: modulePath,
        id: modulePath,
        loaded: false,
      };
      moduleRegistry[modulePath] = localModule;
      if (path.extname(modulePath) === '.json') {
        localModule.exports = this._environment.global.JSON.parse(
          stripBOM(fs.readFileSync(modulePath, 'utf8')),
        );
      } else if (path.extname(modulePath) === '.node') {
        localModule.exports = require(modulePath);
      } else {
        // Only include the fromPath if a moduleName is given. Else treat as root.
        const fromPath = moduleName ? from : null;
        this._execModule(localModule, options, moduleRegistry, fromPath);
      }

      localModule.loaded = true;
    }
    return moduleRegistry[modulePath].exports;
  }

  requireModule(
    from: Config.Path,
    moduleName?: string,
    options?: InternalModuleOptions,
    isRequireActual?: boolean | null,
  ) {
    const moduleID = this._resolver.getModuleID(
      this._virtualMocks,
      from,
      moduleName,
    );
    let modulePath: string | undefined;

    // Some old tests rely on this mocking behavior. Ideally we'll change this
    // to be more explicit.
    const moduleResource = moduleName && this._resolver.getModule(moduleName);
    const manualMock =
      moduleName && this._resolver.getMockModule(from, moduleName);
    if (
      (!options || !options.isInternalModule) &&
      !isRequireActual &&
      !moduleResource &&
      manualMock &&
      manualMock !== this._isCurrentlyExecutingManualMock &&
      this._explicitShouldMock[moduleID] !== false
    ) {
      modulePath = manualMock;
    }

    if (moduleName && this._resolver.isCoreModule(moduleName)) {
      return this._requireCoreModule(moduleName);
    }

    if (!modulePath) {
      modulePath = this._resolveModule(from, moduleName);
    }

    let moduleRegistry;

    if (!options || !options.isInternalModule) {
      if (
        this._moduleRegistry.get(modulePath) ||
        !this._isolatedModuleRegistry
      ) {
        moduleRegistry = this._moduleRegistry;
      } else {
        moduleRegistry = this._isolatedModuleRegistry;
      }
    } else {
      moduleRegistry = this._internalModuleRegistry;
    }

    const module = moduleRegistry.get(modulePath);
    if (module) {
      return module.exports;
    }

    // We must register the pre-allocated module object first so that any
    // circular dependencies that may arise while evaluating the module can
    // be satisfied.
    const localModule: InitialModule = {
      children: [],
      exports: {},
      filename: modulePath,
      id: modulePath,
      loaded: false,
    };
    moduleRegistry.set(modulePath, localModule);

    this._loadModule(
      localModule,
      from,
      moduleName,
      modulePath,
      options,
      moduleRegistry,
    );

    return localModule.exports;
  }