Unit tests: Replace [ExpectedException] with Assert.Throws

[stakx]

There are several unit tests in the UnitTests project that check whether exceptions are thrown when they should be. This is done in two different ways:

• By placing an [ExpectedException(typeof(TException))] custom attribute on the test method, or
• by wrapping a method call or short code block with Assert.Throws<TException>(() => …);.

Using [ExpectedException] is problematic for at least two reasons:

• It is too coarse-grained. It doesn't matter which part of a test method throws. However, speaking in terms of Arrange-Act-Assert, only the Act part of a test method should be tested for exceptions.
• This attribute is no longer supported starting with NUnit version 3, so it would stand in your way if you wanted to migrate to a more recent version of NUnit.

Suggestion: For these two reasons (and, to a minor degree, for consistency's sake) all test methods using [ExpectedException] should be converted to Assert.Throws.