xUnit.net IsType Equivalent in MS Test That Returns Type

Question

I'm following this guide and I'm trying to write a similar test with MS Test. Does MS Test have an IsType() that returns the object when the cast is successful?

From this comparison, I see I can use IsInstanceOfType() but the return type is void.

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I'm trying to implement this line in MS Test: var badRequestResult = Assert.IsType<BadRequestObjectResult>(result);

[Fact]
public async Task IndexPost_ReturnsBadRequestResult_WhenModelStateIsInvalid()
{
    // Arrange
    var mockRepo = new Mock<IBrainstormSessionRepository>();
    mockRepo.Setup(repo => repo.ListAsync()).Returns(Task.FromResult(GetTestSessions()));
    var controller = new HomeController(mockRepo.Object);
    controller.ModelState.AddModelError("SessionName", "Required");
    var newSession = new HomeController.NewSessionModel();

    // Act
    var result = await controller.Index(newSession);

    // Assert
    var badRequestResult = Assert.IsType<BadRequestObjectResult>(result);
    Assert.IsType<SerializableError>(badRequestResult.Value);
}

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Yes, I could cast using as and then use IsInstanceOfType... just wondering if there is a one-liner.

var badRequestResult = result as BadRequestObjectResult;
Assert.IsInstanceOfType(badRequestResult, typeof(BadRequestObjectResult));

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Reference: Add to MSTest Request

Answer 1

There is no equivalent version in MSTest that I have ever come across.

also if casting, then there is no need to check if instance is of type. Just check if it is not null.

// Act
var result = await controller.Index(newSession);

// Assert
var badRequestResult = result as BadRequestObjectResult;
Assert.IsNotNull(badRequestResult, "Expected BadRequestObjectResult");
Assert.IsInstanceOfType(badRequestResult.Value, typeof(SerializableError));

Otherwise, you can create your own assertion

public static class AssertExtension {
    public static TExpected AssertIsType<TExpected>(this object actual, string message = null) 
        where TExpected : class {
        TExpected result = actual as TExpected;
        Assert.IsNotNull(result, message);
        return result;
    }
}

that provides the desired behavior

// Assert
var badRequestResult = result.AssertIsType<BadRequestObjectResult>();
badRequestResult.Value.AssertIsType<SerializableError>();