What's the idiomatic way to verify collection size in xUnit?

Question

I have in my test suite a test that goes something like this:

[Fact]
public void VerifySomeStuff()
{
    var stuffCollection = GetSomeStuff();

    Assert.Equal(         


        

Answer 1

I found this give me the same error:

Assert.Equal(2, vm.Errors.Count());

And casting it stopped the error from appearing.

Assert.Equal(2, (int)vm.Errors.Count());