RSpec is a Behaviour-Driven Development tool for Ruby programmers, and it's popular in many Ruby and Rails projects. MiniTest is the new standard unit testing framework supplied with Ruby 1.9, and it also includes a compact BDD DSL syntax like RSpec. Both of them provide readable and expressive syntax to write test/spec code. This talk will introduce their BDD syntax and its mocks feature. More important, how do we use it to write good unit testing.