make incremental progress Steps: 1. write a failing test 2. write code to make the test pass 3. refactor Also known as: - Test-Driven Development (TDD) - Red/Green/Refactor 12
implement a calculator that can: • add two numbers • calculate factorials Exercise Cadence: I'll start us off. Then we'll mob program the rest, borrowing from the "Who Wants to be a Millionaire" Q&A style. 26
behavior" do it "describes a specific example" do; end context "highlights a special circumstance" do it "describes a specific example" do; end end end end 28
"returns the sum of the two arguments" do setup (required setup) exercise (exercise system under test) verify (result is verified against an expectation) teardown (system under test is reset) end end end 29