This document describes a Jenga game activity used to demonstrate the benefits of test-driven development. The activity involves building a 3-story Jenga tower with blocks, some of which contain defects. Participants undergo three iterations with different testing procedures: in the first, defects are found after building; in the second, defects are found every 10 blocks; in the third, defects are known for each individual block. The goal is to understand how rework effort decreases when testing occurs earlier in the development cycle rather than later.

1. Test First

2. What is this all about
 A game to help us understand the benefits of reducing test cycles
 Teaches us good design
 Helps us understand continuous integration

3. The Rules
 Each team will be given 30 Jenga blocks, numbered 1 to 30
 Each team is required to build a 3 Storied(3 floor) Structure using ALL the
blocks given to them
 Some of the blocks given to the teams will have defects
 The team is unaware of these defective blocks
 At the end of the iteration, teams are expected to have the ready structure

4. Iteration 1
 5 Minutes
 Once the team has built the structure, the team is informed about the
defective block
 Teams need to remove the defective blocks(bugs) from the tower

5. Iteration 2
 5 Minutes
 After every 10 blocks you place, you are told about one defective block
 At the end of 5 minutes, teams need to have the ready structure

6. Iteration 3
 5 minutes
 With every block the team proposes to place into the structure, the team is
informed weather or not the blocks is defective
 At the end of 5 minutes, teams need to have the structure ready

7. Learning
 Rework effort when tests are known late in the cycle
 Uncertainty increases with every piece of untested code goes into the
repository
 Right design –
 The one that exposes bugs(if any)
 The one that does not make the structure very brittle
 Blocks are not tightly coupled with each other or the structure
 Test First – RED-GREEN-REFACTOR