Goodbye Code Review, Hello Pair Programming

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Goodbye Code Review, Hello Pair Programming Appdevcon 2020 Ryosuke Hiramatsu, Shizuna Ito

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Ryosuke Hiramatsu iOS Engineer iOS Engineer Shizuna Ito

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Our team • C2C e-commerce app • 6 iOS developers • released the app 8 months after formed • 5,000,000 DLs • developing with pair programming

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What is pair programming? A development method in which  two engineers write code jointly.

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Working online with “Tuple” https://tuple.app

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Two elements of pair programming TDD Pair Rotation

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Pair Rotation • develop 1 feature per 1 pair 1 2 3

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Pair Rotation • develop 1 feature per 1 pair • 1st day: A and B develop jointly 1 2 3

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Pair Rotation • develop 1 feature per 1 pair • 1st day: A and B develop jointly • 2nd day: A remains and B rotates  1 2 3

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Pair Rotation • develop 1 feature per 1 pair • 1st day: A and B develop jointly • 2nd day: A remains and B rotates • 3rd day: A rotates 1 2 3

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Pair Rotation • develop 1 feature per 1 pair • 1st day: A and B develop jointly • 2nd day: A remains and B rotates • 3rd day: A rotates Avoid relying on individual abilities. Share know-how with the team. 1 2 3

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TDD RED GREEN Refactor

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TDD • Failing test • Implementation code to pass the test • Refactor the code RED GREEN Refactor

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TDD • Failing test • Implementation code to pass the test • Refactor the code Keep the rhythm of pair programming RED GREEN Refactor

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DEMO

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Appdevcon Sticker ¥3,000

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Demo • Simple app making demo

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Demo • Simple app making demo • No documents • test code = speciﬁcation • concentrate on coding

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Demo • Simple app making demo • No documents • test code = speciﬁcation • concentrate on coding • Always teaching • Util class, shortcuts, and etc…

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“Is development speed halved when working in pairs?”

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Number of releases 0 10,000 2,500 5.000 7,500 1,173 1,185 2,829 8,221 Number of Releases Project A B C Our Project (Pair Programming)

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Acceptance failure rate 0% 20% 5% 10% 15% Project A B C Our Project failure rate 11.3% 13.5% 8.6% 0.1% (Pair Programming)

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Familiar with speciﬁcations “Did you become more familiar?” YES 81% 81% NO 19%

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Recap of pair programming

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Recap of pair programming • 1 code with 2 people 

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Recap of pair programming • 1 code with 2 people • more effective with pair-rotation and TDD

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Recap of pair programming • 1 code with 2 people • more effective with pair-rotation and TDD • always develop with feedback 

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What I felt from experience • Always talk. A lot of communication • Communication brings respect and understanding • Essential for creativity of the team  Respect High quality products Communication