gistfile1.txt

func test_refresh_loadsDataFromAPI() {
    // given 
    mockAPI.stubFetchResponse = .success([])
    let exp = expectation(description: #function)

    // when 
    viewModel.refresh()
    mockAPI.didFetchData = { exp.fulfill() }

    // then 
    waitForExpectations(timeout: 1)
    XCTAssertTrue(mockAPI.fetchDataCalled) // ✅ pass 
}