It looks like the issue you're encountering is related to the types of the `Exit` values you're c...

it.effect('should return error', () =>
  Effect.gen(function* () {
    const { getTokens } = yield* Tokens;
    const result = yield* getTokens({ cookie: '12345' }).pipe(Effect.flip, Effect.exit);

    expect(result).toEqual(Exit.fail(HttpError.unauthorized()));
  }).pipe(Effect.provide(Layer.provideMerge(mockTokens, mockRequest))),
);

const result: Exit.Exit<HttpError.HttpError, TokenResponseBody>

    const failure = Exit.fail(HttpError.unauthorized());

const failure: Exit.Exit<never, HttpError.HttpError>

const failure: Exit.Exit<never, HttpError.HttpError>
const result: Exit.Exit<HttpError.HttpError, TokenResponseBody>