Test Driven Development Ben Hoskins Test Driven Development

Test Driven Development Ben Hoskins

Test Driven Development

a. k. a. Contract First Development (Design by Contract (C))

a. k. a. Behaviour Driven Development

With a little help from Domain Driven Design

Test Driven Development Setup Exercise function Assert Teardown

Contract First Development Acceptable and unacceptable input values Preconditions Return values Exception that can occur, and their meanings Side effects Postconditions Invariants Performance guarantees

Behaviour Driven Development Given When Then

Behaviour Driven Development Given Acceptable and unacceptable input values Invariants Preconditions When Event to trigger the function under development Then Return values Exception that can occur, and their meanings Side effects Postconditions Invariants Performance guarantees

Test Driven Development Setup Given Acceptable and unacceptable input values Preconditions Execute function When Event to trigger the function under development Assert Then Return values etc. . . Tear Down

Test Driven Development. . . with a little help from Domain Driven Design @Test public void can. Calculate. ASingle. Value() { Persona henry = Persona. Factory. sensible. Defaults(). and("Henry. Humble"); String share. Value = Test. Constants. SINGLE_SHARE_VALUE; Share. Calculator share. Calculator=new Share. Calculator(driver, share. Value); henry. enter. Share. Amount. Into(share. Calculator); Assert. assert. Equals("1. 65", share. Calculator. get. Total. Value()); }

Test Driven Development. . . with a little help from Domain Driven Design @Test public void can. Calculate. ASingle. Value() { Persona henry = Persona. Factory. sensible. Defaults(). and("Henry. Humble"); String share. Value = Test. Constants. SINGLE_SHARE_VALUE; Share. Calculator share. Calculator=new Share. Calculator(driver, share. Value); henry. enter. Share. Amount. Into(share. Calculator); Assert. assert. Equals("1. 65", share. Calculator. get. Total. Value()); } The behaviour is: Share Calculator can calculate a single value

Test Driven Development. . . with a little help from Domain Driven Design @Test public void can. Calculate. ASingle. Value() { Persona henry = Persona. Factory. sensible. Defaults(). and("Henry. Humble"); String share. Value = Test. Constants. SINGLE_SHARE_VALUE; Share. Calculator share. Calculator=new Share. Calculator(driver, share. Value); henry. enter. Share. Amount. Into(share. Calculator); Assert. assert. Equals("1. 65", share. Calculator. get. Total. Value()); } The setup / givens are: Henry Humble, a shareholder with 1 share, A share value of 1. 65

Test Driven Development. . . with a little help from Domain Driven Design @Test public void can. Calculate. ASingle. Value() { Persona henry = Persona. Factory. sensible. Defaults(). and("Henry. Humble"); String share. Value = Test. Constants. SINGLE_SHARE_VALUE; Share. Calculator share. Calculator=new Share. Calculator(driver, share. Value); henry. enter. Share. Amount. Into(share. Calculator); Assert. assert. Equals("1. 65", share. Calculator. get. Total. Value()); } The execute function / when is: Henry Humble enters his share amount into The share calculator

Test Driven Development. . . with a little help from Domain Driven Design @Test public void can. Calculate. ASingle. Value() { Persona henry = Persona. Factory. sensible. Defaults(). and("Henry. Humble"); String share. Value = Test. Constants. SINGLE_SHARE_VALUE; Share. Calculator share. Calculator=new Share. Calculator(driver, share. Value); henry. enter. Share. Amount. Into(share. Calculator); Assert. assert. Equals("1. 65", share. Calculator. get. Total. Value()); } The assert / then is: The share calculator shows a total value of 1. 65

Test Driven Development. . . with a little help from Domain Driven Design In our example there domain driven design was applied to the test: The behaviour: A person can input their shares into the share calculator, the share calculator displays the total value of the shares. The domain: A fixed share price, A share calculator, can calculate a share price, has the total value available, A Person, with a fixed amount of shares