title: Unittest tests order
body: <p>How can I be sure of the unittest methods' order? Is the alphabetical or numeric prefixes the proper way?</p>
  <pre><code>class TestFoo(TestCase):
      def test_1(self):
          ...
      def test_2(self):
          ...
  </code></pre>
  <p>or</p>
  <pre><code>class TestFoo(TestCase):
      def test_a(self):
          ...
      def test_b(self):
          ...
  </code></pre>