如何使用NUnit測試MvvmCross MvxCommand <int>

Question

當我的命令需要使用類型爲整數的CommandParameter時，如何爲MvvmCross MvxCommand編寫NUnit測試。

testListViewModel.EditCommand.Execute(null); 

這是不是一個選項，因爲我有這個ViewModel。如果傳遞參數，CanExecute會繼續。

public class TestListViewModel : MvxViewModel 
{ 
    private readonly ITestService _testService; 
    private readonly IDialogService _dialogService; 
    public TestListViewModel(ITestService testService, IDialogService dialogService) 
    { 
     _testService = testService; 
     _dialogService = dialogService; 
    } 

    public MvxCommand<int> EditCommand { get { return new MvxCommand<int>(Edit, id => id > 0); } }  

    private void Edit(int asTestID) { ShowViewModel<TestViewModel>(new { asTestID }); } 
} 

我使用NUnit +最小起訂量+ Cirrious.MvvmCross.Test.Core引用在我的測試項目，並有這樣的結構。

public class MockDispatcher : MvxMainThreadDispatcher, IMvxViewDispatcher 
{ 
    public readonly List<MvxViewModelRequest> Requests = new List<MvxViewModelRequest>(); 
    public readonly List<MvxPresentationHint> Hints = new List<MvxPresentationHint>(); 
    public bool RequestMainThreadAction(Action action) 
    { 
     action(); 
     return true; 
    } 

    public bool ShowViewModel(MvxViewModelRequest request) 
    { 
     Requests.Add(request); 
     return true; 
    } 

    public bool ChangePresentation(MvxPresentationHint hint) 
    { 
     Hints.Add(hint); 
     return true; 
    } 
} 

[TestFixture] 
class TestListViewModelTest : MvxIoCSupportingTest 
{ 
    [Test] 
    public void TestListViewModel_OnEdit_ShowTestViewModel() 
    { 
     //Arrange 
     base.ClearAll(); 

     var mockDispatcher = new MockDispatcher(); 
     Ioc.RegisterSingleton<IMvxViewDispatcher>(mockDispatcher); 
     Ioc.RegisterSingleton<IMvxMainThreadDispatcher>(mockDispatcher); 

     var mockDialogService = new Mock<IDialogService>(); 
     var mockTestService = new Mock<ITestService>(); 

     var testListViewModel = new TestListViewModel(mockTestService.Object, mockDialogService.Object); 

     //Act 
     testListViewModel.EditCommand.Execute(2); //this line is failing 

     //Assert 
     Assert.AreEqual(1, mockDispatcher.Requests.Count); 
     var request = mockDispatcher.Requests[0]; 
     Assert.AreEqual(typeof(TestViewModel), request.ViewModelType); 
     Assert.AreEqual((2).ToString(), request.ParameterValues["asTestID"]); 
    } 
} 

當我運行測試它拋出MvxIoCResolveException這個調用堆棧。我試圖調試它，並且我的代碼在MvxNavigatingObject.ShowViewModel（）上的字面失敗，其中參數是一個對象，並嘗試調用parameterValuesObject.ToSimplePropertyDictionary（）。
在靜態函數ToSimplePropertyDictionary（此對象輸入）propertyInfos枚舉爲空，所以它不能調用的foreach（在propertyInfos變種的PropertyInfo）。

調用堆棧，我從運行測試得到的是：

Cirrious.CrossCore.Exceptions.MvxIoCResolveException : Failed to resolve type Cirrious.MvvmCross.Platform.IMvxStringToTypeParser 
    at Cirrious.CrossCore.IoC.MvxSimpleIoCContainer.Resolve(Type t) 
    at Cirrious.CrossCore.IoC.MvxSimpleIoCContainer.Resolve() 
    at Cirrious.MvvmCross.MvxSingletonCache.get_Parser() 
    at Cirrious.MvvmCross.Platform.MvxSimplePropertyDictionaryExtensionMethods.<ToSimplePropertyDictionary>b__7(PropertyInfo property) 
    at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext() 
    at Cirrious.MvvmCross.Platform.MvxSimplePropertyDictionaryExtensionMethods.ToSimplePropertyDictionary(Object input) 
    at Cirrious.MvvmCross.ViewModels.MvxNavigatingObject.ShowViewModel(Object parameterValuesObject, IMvxBundle presentationBundle, MvxRequestedBy requestedBy) 
    at App.Core.ViewModels.TestListViewModel.Edit(Int32 asTestID) in TestListViewModel.cs: line 37 
    at App.Tests.Test.TestListViewModelTest.TestListViewModel_OnEdit_ShowTestViewModel() in TestListViewModelTest.cs: line 97 

任何幫助，將不勝感激！

Answer 1

當您使用參數調用ShowViewModel時，有幾種不同的方法可以做到這一點。這決定了MvvmCross如何調用您的Init方法。

• 個別簡單類型參數
• 與簡單類型屬性
• 如InitFromBundle（）與IMvxBundle參數的單個類型化參數對象 - 這最後風味總是通過IMvxViewModel接口支持。

您正在使用匿名類型調用ShowViewModel，但沒有屬性名稱。這些屬性名稱必須與Init方法中的參數名稱匹配。

因此，不是這樣的：

private void Edit(int asTestID) { ShowViewModel<TestViewModel>(new { asTestID }); } 

這樣做：

// simply-Typed parameters 
private void Edit(int asTestID) { ShowViewModel<TestViewModel>(asTestID); } 

或者這樣：

// a single Typed parameter object with simply-Typed properties 
private void Edit(int asTestID) { ShowViewModel<TestViewModel>(new { ID = asTestID }); } 

見https://github.com/MvvmCross/MvvmCross/wiki/View-Model-Lifecycle#2-init

Answer 2

// for navigation parsing 
    Ioc.RegisterSingleton<IMvxStringToTypeParser>(new MvxStringToTypeParser()); 

請參閱 https://github.com/MvvmCross/MvvmCross/wiki/Testing