xUnit2021 v2 v3 Error

Async assertions should be awaited

Cause

If you use an async assertion, you must await the result.

Reason for rule

Calling an async assertion without awaiting the result will result in false positives, because the test framework cannot follow the result of the async operation (and any errors will be thrown away).

How to fix violations

To fix a violation of this rule, await the result of the async assertion.

Examples

Violates

using System;
using Xunit;

public class xUnit2021
{
    [Fact]
    public void TestMethod()
    {
        Assert.ThrowsAsync<DivideByZeroException>(async () => throw new DivideByZeroException());
    }
}

Does not violate

using System;
using Xunit;

public class xUnit2021
{
    [Fact]
    public async Task TestMethod()
    {
        await Assert.ThrowsAsync<DivideByZeroException>(async () => throw new DivideByZeroException());
    }
}