How to unit test ActionFilterAttribute's OnActionExecuting() with Xunit [duplicate]

问题

This is in ASP.net core 3.1, using XUnit and NSubstitute (Limited to these frameworks by business rules)

I have a ActionFilterAttribute derived model validation filter, (taken from this article: Validate the Model State Globally in .NET Core), that I need to unit test.

I'm having trouble getting the tests to work because I am getting null back regardless of what I try.

The test code below is based on this Stack Overflow post from 2017: How to unit test ActionFilterAttribute

The code I want to test:

public class ModelStateAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext context)
    {
        if (!context.ModelState.IsValid)
        {
            context.Result = new BadRequestObjectResult(context.ModelState);
        }
    }
}

My test

public class ModelStateAttributeTests
{
    private readonly IFileCache _fileCache = new FileCache();

    [Fact]
    public void OnActionExecuting_ShouldNotBeNull()
    {
        //Arrange
        var httpContext = new DefaultHttpContext();
        var context = new ActionExecutingContext(
            new ActionContext
            {
                HttpContext = httpContext,
                RouteData = new RouteData(),
                ActionDescriptor = new ActionDescriptor(),
            },
            new List<IFilterMetadata>(),
            new Dictionary<string, object>(), new TestController(_fileCache));
        var sut = new ModelStateAttribute();

        //Act
        sut.OnActionExecuting(context);

        //Assert
        context.Result.Should().NotBeNull();
    }
}

Error message:

Test Name:  AppName.Tests.Attributes.ModelStateAttributeTests.OnActionExecuting_ShouldNotBeNull
Test FullName:  AppName.Tests.AppName.Tests.Attributes.ModelStateAttributeTests.AppName.Tests.Attributes.ModelStateAttributeTests.OnActionExecuting_ShouldNotBeNull
Test Source:    C:\repos\AppName\AppName.Tests\Attributes\ModelStateAttributeTests.cs : line 20
Test Outcome:   Failed
Test Duration:  0:00:00

Test Name:  AppName.Tests.Attributes.ModelStateAttributeTests.OnActionExecuting_ShouldNotBeNull
Test Outcome:   Failed
Result StackTrace:  
at FluentAssertions.Execution.XUnit2TestFramework.Throw(String message)
   at FluentAssertions.Execution.TestFrameworkProvider.Throw(String message)
   at FluentAssertions.Execution.DefaultAssertionStrategy.HandleFailure(String message)
   at FluentAssertions.Execution.AssertionScope.FailWith(Func`1 failReasonFunc)
   at FluentAssertions.Execution.AssertionScope.FailWith(Func`1 failReasonFunc)
   at FluentAssertions.Execution.AssertionScope.FailWith(String message, Object[] args)
   at FluentAssertions.Primitives.ReferenceTypeAssertions`2.NotBeNull(String because, Object[] becauseArgs)
   at AppName.Tests.Attributes.ModelStateAttributeTests.OnActionExecuting_ShouldNotBeNull()
Result Message: Expected object not to be <null>.

来源：https://stackoverflow.com/questions/60755839/how-to-unit-test-actionfilterattributes-onactionexecuting-with-xunit

标签

unit-testing

asp.net-core

testing

xunit