rspec-expectations ships with a number of built-in matchers. Each matcher can be used with expect(..).to or expect(..).not_to to define positive and negative expectations respectively on an object. Most matchers can also be accessed using the (...).should and (...).should_not syntax; see using should syntax for why we recommend using expect. e.g. expect(result).to eq(3) expect(list).not_to be_empt