title: Why doesn't MiniTest::Spec have a wont_raise assertion?
body: <p>Ruby's <code>Test::Unit</code> has <code>assert_nothing_raised</code>. <code>Test::Unit</code> has been replaced by <a href="https://github.com/seattlerb/minitest" rel="noreferrer">MiniTest</a>. Why don't MiniTest's assertions / expectations have anything parallel to this? For example you can expect <code>must_raise</code> but not <code>wont_raise</code>.</p>