Why testFixture instead of TestClass?

Question

There are three ways to organize unit tests: Text per Fixture, Class or Feature. But NUnit attribute for TestClass is called TestFixture. Are there any historical reasons for that?

Answer 1

Now that you ask about it, I just looked it up.
A test fixture is the fixed baseline state that must be established before the tests are run, such that the results are predictable and repeatable. In unit testing frameworks, we use the SetUp and TearDown attributes/methods to create/destroy the test fixture (e.g. initialize instance variables with the right objects).