xUnit2015 Warning

Do not use typeof expression to check the exception type

Cause

This rule is triggered when using the non-generic version of Assert.Throws along with a typeof expression.

Reason for rule

When the expected type is known at compile-time, the generic overload should be used. In addition to being more concise, it also returns the exception cast to the appropriate type when the assert succeeds, for use in later assertions.

How to fix violations

To fix a violation of this rule, use the generic version of Assert.Throws.

Examples

Violates

using System;
using Xunit;

public class xUnit2015
{
    void FunctionThatThrows() { }

    [Fact]
    public void TestMethod()
    {
        Assert.Throws(typeof(InvalidOperationException), () => FunctionThatThrows());
    }
}

Does not violate

using System;
using Xunit;

public class xUnit2015
{
    void FunctionThatThrows() { }

    [Fact]
    public void TestMethod()
    {
        Assert.Throws<InvalidOperationException>(() => FunctionThatThrows());
    }
}