如何在 ASP.net 核心中為自定義模型綁定器編寫單元測試

Question

我已經為一個屬性編寫了自定義模型綁定器。 現在我正在嘗試為其編寫單元測試，但無法為模型綁定器創建對象。 誰能幫我 ？ 以下是我必須為其編寫測試的代碼。

public class JourneyTypesModelBinder : IModelBinder
{
    public Task BindModelAsync(ModelBindingContext bindingContext)
    {
        bool IsSingleWay = Convert.ToBoolean((bindingContext.ValueProvider.GetValue("IsSingleWay")).FirstValue);
        bool IsMultiWay = Convert.ToBoolean((bindingContext.ValueProvider.GetValue("IsMultiWay")).FirstValue);

        JourneyTypes journeyType = JourneyTypes.None;
        bool hasJourneyType = Enum.TryParse((bindingContext.ValueProvider.GetValue("JourneyType")).FirstValue, out journeyType);
        if (!hasJourneyType)
        {
            if (IsSingleWay)
                journeyType = JourneyTypes.Single;
            else journeyType = JourneyTypes.MultiWay;
        }

        bindingContext.Result = ModelBindingResult.Success(journeyType);
        return Task.CompletedTask;
    } }  

Answer 1

我已經使用 Nunit 創建了單元測試（這與 XUnit 幾乎相同）並且我使用 Moq 模擬了依賴項。 由於在線 C# 編譯器可能會出現一些錯誤，但下面顯示的代碼會給你一個想法。

[TestFixture]
public class BindModelAsyncTest()
{
    private JourneyTypesModelBinder _modelBinder;
    private Mock<ModelBindingContext> _mockedContext;

    // Setting up things
    public BindModelAsyncTest()
    {
        _modelBinder = new JourneyTypesModelBinder();
        _mockedContext = new Mock<ModelBindingContext>();

        _mockedContext.Setup(c => c.ValueProvider)
            .Returns(new ValueProvider() 
            {
                // Initialize values that are used in this function
                // "IsSingleWay" and the other values
            });
    }

    private JourneyTypesModelBinder CreateService => new JourneyTypesModelBinder();

    [Test]                       
    public Task BindModelAsync_Unittest()
    {
        //Arrange
        //We set variables in setup function.
        var unitUnderTest = CreateService();

        //Act
        var result = unitUnderTest.BindModelAsync(_mockedContext);

        //Assert
        Assert.IsNotNull(result);
        Assert.IsTrue(result is Task.CompletedTask);
    }
} 

Answer 2

您可以使用實例DefaultModelBindingContext傳遞到BindModelAsync() ：

    [Fact]
    public void JourneyTypesModelBinderTest()
    {
        var bindingContext = new DefaultModelBindingContext();

        var bindingSource = new BindingSource("", "", false, false);
        var routeValueDictionary = new RouteValueDictionary
        {
            {"IsSingleWay", true},
            {"JourneyType", "Single"}
        };
        bindingContext.ValueProvider = new RouteValueProvider(bindingSource, routeValueDictionary);

        var binder = new JourneyTypesModelBinder();
        binder.BindModelAsync(bindingContext);

        Assert.True(bindingContext.Result.IsModelSet);
        Assert.Equal(JourneyTypes.Single, bindingContext.Result.Model);
    }

這可以替代為bindingContext使用模擬對象。