我如何使用 Shouldly 进行自定义断言并维护特定于调用站点的断言消息？

Question

我在我的 xUnit 测试中使用 the excellent Shouldly library，我发现自己在不同的测试中使用了断言的集合序列，所以我将它们组合到新的断言扩展方法中 - 但是当我这样做时我丢失了 Shouldly 的上下文断言消息。

这是我的旧代码，它与 Shouldly 一起工作以在 Shouldly 断言错误中包含源代码级信息和调用站点上下文：

[Fact]
public void Dict_should_contain_valid_Foobar_Bar_entry()
{
    IDictionary<String,Bar> dict = ...
    dict.TryGetValue( "Foobar", out Bar bar ).ShouldBeTrue();
    bar.ShouldNotBeNull();
    bar.ChildList.Count.ShouldBe( expected: 3 );
    bar.Message.ShouldBeNull();
}

[Fact]
public void Dict_should_contain_valid_Barbaz_Bar_entry()
{
    IDictionary<String,Bar> dict = ...
    dict.TryGetValue( "Barbaz", out Bar bar ).ShouldBeTrue();
    bar.ShouldNotBeNull();
    bar.ChildList.Count.ShouldBe( expected: 3 );
    bar.Message.ShouldBeNull();
}

我在同一项目中将其转换为这种新的扩展方法：

public static void ShouldBeValidBar( this IDictionary<String,Bar> dict, String barName )
{
    dict.ShouldNotBeNull();
    dict.TryGetValue( barName, out Bar bar ).ShouldBeTrue();
    bar.ShouldNotBeNull();
    bar.ChildList.Count.ShouldBe( expected: 3 );
    bar.Message.ShouldBeNull();
}

因此我的测试更改为：

[Fact]
public void Dict_should_contain_valid_Foobar_Bar_entry()
{
    IDictionary<String,Bar> dict = ...
    dict.ShouldBeValidBar( "Foobar" );
}

[Fact]
public void Dict_should_contain_valid_Barbaz_Bar_entry()
{
    IDictionary<String,Bar> dict = ...
    dict.ShouldBeValidBar( "Barbaz" );
}

...但现在我的 Shouldly assert 消息不包含来自 Dict_should_contain_valid_Foobar_Bar_entry 的任何上下文信息，而是仅包含来自 ShouldBeValidBar.

的上下文

如何指示 Shouldly 忽略 ShouldBeValidBar 的上下文并改用其父调用站点？

Answer 1

长话短说：

将 [ShouldlyMethods] 属性添加到您的自定义断言扩展方法类（不是单独的扩展方法）：

[ShouldlyMethods] // <-- This, right here!
public static class MyShouldlyAssertions
{
    public static void ShouldBeValidBar( this IDictionary<String,Bar> dict, String barName )
    {
        [...]
    }
}

长版：

经过一些谷歌搜索后， - and after reading the source of Shouldly's secret-sauce: SourceCodeTextGetter, I see that it determines which entries in the stack-trace can be overlooked by the presence of the [ShouldlyMethods] attribute (Shouldly.ShouldlyMethodsAttribute) 在堆栈跟踪的每个帧中包含方法的类型：

void ParseStackTrace(StackTrace trace)
{
    [...]

    while (ShouldlyFrame == null || currentFrame.GetMethod().IsShouldlyMethod())
    {
        if (currentFrame.GetMethod().IsShouldlyMethod())
            ShouldlyFrame = currentFrame;

        [...]
    }

    [...]
}

internal static bool IsShouldlyMethod(this MethodBase method)
{
    if (method.DeclaringType == null)
        return false;

    return
        method
            .DeclaringType
            .GetCustomAttributes( typeof(ShouldlyMethodsAttribute), true )
            .Any()
        ||
        (
            method.DeclaringType.DeclaringType != null
            && 
            method
                .DeclaringType
                .DeclaringType
                .GetCustomAttributes( typeof(ShouldlyMethodsAttribute), true )
                .Any()
        );
}

所以只需将 [ShouldlyMethods] 属性添加到我的扩展方法的容器中即可类:

[ShouldlyMethods]
public static class ShouldlyAssertionExtensions
{    
    public static void ShouldBeValidBar( this IDictionary<String,Bar> dict, String barName )
    {
        dict.ShouldNotBeNull();
        dict.TryGetValue( barName, out Bar bar ).ShouldBeTrue();
        bar.ShouldNotBeNull();
        bar.ChildList.Count.ShouldBe( expected: 3 );
        bar.Message.ShouldBeNull();
    }
}

现在我的断言错误具有 ShouldBeValidBar 的调用站点的上下文。万岁！

我如何使用 Shouldly 进行自定义断言并维护特定于调用站点的断言消息？

How can I have custom asserts with Shouldly and maintain the call-site-specific assertion messages?

c#

unit-testing

assert

xunit

shouldly

长话短说：

长版：