NSubstitute - 模拟任何参数的参数行为 [英] NSubstitute - mock out parameter behaviour for any parameter

问题描述

我正在尝试使用 NSubstitute 模拟 IConfigurationProvider.我需要方法 bool TryGet(string key, out string value) 来返回不同键的值.所以是这样的:

I'm trying to mock IConfigurationProvider with NSubstitute. I need the method bool TryGet(string key, out string value) to return values for differing keys. So something like this:

var configProvider = Substitute.For<IConfigurationProvider>();
configProvider.TryGet("key1", out Arg.Any<string>()).Returns(x => 
    { x[1] = "42"; return true; });

但这不能编译.我需要模拟方法将 out 参数实际设置为适当的值，无论该参数是什么 - 它是一个依赖项，被测单元使用自己的参数调用此方法，我只希望它返回"(如通过填写 out 参数返回)正确的键值.

but this does not compile. I need the mocked method to actually set the out parameter to the appropriate value, regardless of what that parameter is - it's a dependency, the unit under test calls this method with its own parameters and I just want it to "return" (as in return by filling the out parameter) correct values for keys.

这应该可以让您更深入地了解问题:

This should give more perspective on the problem:

var value = "";
var configProvider = Substitute.For<IConfigurationProvider>();
configProvider
.TryGet("key1", out value)
.Returns(x => { 
    x[1] = "42"; 
    return true; 
});

var otherValue = "other";
configProvider.TryGet("key1", out value);
configProvider.TryGet("key1", out otherValue);

Assert.AreEqual("42", value);      // PASS.
Assert.AreEqual("42", otherValue); // FAIL.

我需要两个断言都为真，因为这个方法将被测试类使用，并且可以自由地传递它想要的任何输出参数，我只需要用42"填充它.

I need both assertions to be true, since this method will be used by the tested class and it's free to pass any out parameter it wants, I just need to fill it with "42".

推荐答案

configProvider.TryGet("key1", out Arg.Any()) 不是有效的 C# 语法，它是为什么它不会编译.

configProvider.TryGet("key1", out Arg.Any<string>()) is not valid C# syntax, which is why it wont compile.

您需要为 out 参数使用实际变量.

You need to use an actual variable for the out parameter.

以下在测试时有效.

//Arrange            
var expectedResult = true;
var expectedOut = "42";
var actualOut = "other";
var anyStringArg = Arg.Any<string>();
var key = "key1";
var configProvider = Substitute.For<IConfigurationProvider>();
configProvider
    .TryGet(key, out anyStringArg)
    .Returns(x => {
        x[1] = expectedOut;
        return expectedResult;
    });

//Act
var actualResult = configProvider.TryGet(key, out actualOut);

//Assert
Assert.AreEqual(expectedOut, actualOut); // PASS.
Assert.AreEqual(expectedResult, actualResult); // PASS.

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