Moq 如何针对可选参数 mock 以及如何直接返回传入的参数值
0
悬赏园豆：30
[已解决问题]
解决于 2024-01-21 12:15
今天在测试中需要用 Mock 对下面的接口进行 mock
public interface IMarkdownClient
{
Task<string> RenderAsync(string text, MarkdownRenderOption opt, bool allowFallback = true, CancellationToken cancellationToken = default(CancellationToken));
}
尝试用下面的代码进行 mock
markdownClient.Setup(x => x.RenderAsync(It.IsAny<string>(), It.IsAny<MarkdownRenderOption>()))
却报错
CS0854 - An expression tree may not contain a call or invocation that uses optional arguments.
最佳答案
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通过 Comparing mocking frameworks: How to handle optional parameter with NSubstituite, Moq and FakeItEasy 知道了，Moq 不支持可选参数，必须要给可选参数传值
var markdownClient = new Mock<IMarkdownClient>();
markdownClient.Setup(x => x.RenderAsync(
It.IsAny<string>(),
It.IsAny<MarkdownRenderOption>(),
It.IsAny<bool>(),
It.IsAny<CancellationToken>()));
原因是
This is not actually an issue with the mocking frameworks but rather the underlying expression tree API that doesn't support optional arguments
直接返回传入的 text 参数值，通过下面的代码解决了
ReturnsAsync<string, MarkdownRenderOption, bool, CancellationToken, IMarkdownClient, string>((x, y, z, _) => x)
其中第1-4个类型是 RenderAsync 方法的4个参数类型，IMarkdownClient 是所 mock 的接口，最后一个 string 是方法返回值的类型
完整代码如下：
var markdownClient = new Mock<IMarkdownClient>();
markdownClient.Setup(x => x.RenderAsync(
It.IsAny<string>(),
It.IsAny<MarkdownRenderOption>(),
It.IsAny<bool>(),
It.IsAny<CancellationToken>()))
.ReturnsAsync<string, MarkdownRenderOption, bool, CancellationToken, IMarkdownClient, string>((x, y, z, _) => x);
