配置NSubstitute模拟ValidateAndThrowAsync抛异常时单元测试失败求助

The error occurs because you’re combining argument matching (Arg.Any<Entity>()) with ThrowsAsyncForAnyArgs, which creates a conflict in NSubstitute’s call tracking. ThrowsAsyncForAnyArgs is designed to match any arguments for a method, so using Arg.Any alongside it confuses NSubstitute about which call configuration to apply.

Solution 1: Use ThrowsAsync with Argument Matching #

Replace ThrowsAsyncForAnyArgs with ThrowsAsync when you explicitly use Arg.Any to match arguments:

_validator
    .ValidateAndThrowAsync(Arg.Any<Entity>())
    .ThrowsAsync(new ValidationException(string.Empty));

Solution 2: Use ThrowsAsyncForAnyArgs without Explicit Argument Matching #

If you want to match any call to ValidateAndThrowAsync regardless of arguments, omit Arg.Any and use a dummy parameter (like default) in the method call:

_validator
    .ValidateAndThrowAsync(default)
    .ThrowsAsyncForAnyArgs(new ValidationException(string.Empty));

Corrected Full Code #

Here’s the fixed version using Solution 1:

using System;
using System.Threading.Tasks;
using FluentValidation;
using NSubstitute;
using NSubstitute.ExceptionExtensions;
using FluentAssertions;

public class Program
{
    private IValidator<Entity> _validator;

    public static async Task Main()
    {
        var program = new Program();
        await program.Test();
    }

    public async Task Test()
    {
        var entity = new Entity();
        _validator = Substitute.For<IValidator<Entity>>();
        // Fixed configuration here
        _validator
            .ValidateAndThrowAsync(Arg.Any<Entity>())
            .ThrowsAsync(new ValidationException(string.Empty));

        var testMethod = async () => await CreateAsync(entity);

        await testMethod.Should().ThrowAsync<ValidationException>();
    }

    public async Task CreateAsync(Entity entity)
    {
        await _validator.ValidateAndThrowAsync(entity);
    }

    public class Entity { }
}

This properly configures the substitute to throw a ValidationException when ValidateAndThrowAsync is called with any Entity, resolving the NSubstitute call tracking error.

内容的提问来源于stack exchange，提问作者Erik Philips