public async Task GetVehicleListAsync_WithAllVehicles_ReturnVehicleResponse() { // Arrange var vehicles = new List <Vehicle> { new Vehicle { Id = Guid.NewGuid(), VehicleId = 1, Number = "A-001", Model = "Honda City", Description = "Blue Color" } }; vehiclesRepository.GetVehicleListAsync().Returns(Task.FromResult(vehicles)); // Act var responses = await vehiclesService.GetVehicleListAsync(); // Assert Assert.NotNull(responses); Assert.True(responses.Count > 0); Assert.IsType <List <VehicleResponse> >(responses); }