Advantages of pairing and TDD

Tom Dane

Research on pairing

• Experiment at University of Utah.
• Subjects were Senior Software Engineering students.
• Needed to complete 3 projects.
• Half paired, half worked alone.

Speed

With practice, pairing only 15% slower.

Bugs

Code written when pairing passed more tests

Tech debt

Pairs write less code!

Other benefits

Less knowledge loss when:

• people are sick
• on vacation
• leave the company

Be pragmatic

• Not suitable for every task.
• Pairing is a skill, and takes time to learn.

Research on TDD

• Studies done by IBM and Microsoft.
• Teams worked with same product, language, and manager.
• One team used TDD, one did not.

Results

• Short term, teams using TDD were 15% - 35% slower.
• But long term, much faster.
• Why? Teams using TDD shipped between 40% and 90% fewer bugs.

"If it doesn't have to work, I can get it done a lot faster" Kent Beck, Inventor of TDD