How mock module with TypeScript?

[cawa-93]

I'm trying to mock the BrowserWindow class from the electron module.

This class is used as a constructor new BrowserWindow(...) and also has static methods BrowserWindow.getAllWindows().

I wrote mock and tests. And everything works. But I get a warning from the TypeScript, which is logical.

// TS2339: Property 'mock' does not exist on type 'typeof BrowserWindow'.
expect(BrowserWindow.mock.instances.length).toBe(1);

I tryed use MockedObject helper. And in part it helped. Static methods are now defined correctly. But there is no access to instance methods:

// @ts-expect-error
const BrowserWindowMocked = BrowserWindow as MockedObject<typeof BrowserWindow>;

expect(BrowserWindowMocked.getAllWindows.mock.calls.length).toEqual(0); // Ok

//  Property 'loadURL' does not exist on type '[options?: BrowserWindowConstructorOptions]'.
expect(BrowserWindowMocked.mock.instances[0].loadURL).toHaveBeenCalledTimes(1);

My full demo can be founded here: https://github.com/cawa-93/vite-electron-builder/blob/3d81e3793da77ba56f40f5a5ad3531feb9568ee8/packages/main/tests/unit.spec.ts

[cawa-93]

Type below works for me

type TBrowserWindowMocked = typeof BrowserWindow
  & MockedObjectDeep<typeof BrowserWindow>
  & JestMockCompatFn<ConstructorParameters<typeof BrowserWindow>, MockedObjectDeep<BrowserWindow>>;

const BrowserWindowMocked = BrowserWindow as TBrowserWindowMocked 

Full test may be found here: https://github.com/cawa-93/vite-electron-builder/blob/cafa809218ae52a311beaee3bcc86f97abb3fabe/packages/main/tests/unit.spec.ts

[sheremet-va]

We have a type hint method for that:

You can use vi.mocked(BrowserWindow).mock.instances.length

[cawa-93]

Awesome. Thanks

[cawa-93]

It seems that this helper does not mock the properties of the class instance:

// Property 'mockReturnValueOnce' does not exist on type '(url: string, options?: LoadURLOptions) => Promise '.
vi.mocked(BrowserWindow, true).mock.instances[0].loadURL.mockReturnValueOnce(true)

I fix this by adding:

vi.mocked(BrowserWindow as typeof BrowserWindow
  & JestMockCompatFn<ConstructorParameters<typeof BrowserWindow>, MaybeMockedDeep<BrowserWindow>> )

[cawa-93]

... or just use vi.mocked twice:

const mockedBW = vi.mocked(BrowserWindow)
const instance = vi.mocked(mockedBW.mock.instances[0])