Testing for exceptions with [TestCase] attribute in NUnit 3?

I agree with the Corpus Gigantus's answer but why don't you simplify thing like this:

[TestCase(-10, 2, -5)]
[TestCase(-1, 2, -0.5)]
[TestCase(-1, 0, null, typeof(ArgumentException))]
public void TestDivide(double a, double b, double result, Type exception = null)
{
    if(exception != null)
    {
        Assert.Throws(exception, delegate { _uut.Divide(a, b);  });
                
    } else Assert.That(_uut.Divide(a, b), Is.EqualTo(result));
}

In this way, the expected exception is part of the test parameters as well, note that you can only have two outcome, either the division succeeds or throws.

ExpectedException would have been the correct method for NUnit 2.X, but it was removed from NUnit 3.

There's a various snippets of discussion in the NUnit Google Group and the equivalent Dev group - but it looks like the decision was made that it's generally a better design pattern to test expected outcomes, and exceptions in separate methods. (link)

The only way to do this in NUnit 3, would be to break it down in to two separate tests. (Confirmed in a similar question answered by the NUnit core team, here.)

[TestCase(-10, 2, -5)]
[TestCase(-1, 2, -0.5)]
public void TestDivide(double a, double b, double result)
{
    Assert.That(_uut.Divide(a, b), Is.EqualTo(result));
}

[TestCase(-1, 0)]
public void TestDivideThrows(double a, double b)
{
    Assert.That(() => _uut.Divide(a, b), Throws.TypeOf<ArgumentException>());
}