CodeAndroid meetup Test Driven Development

Objectives Brief history of TDD Do a very basic test

Apologies upfront: Easily excited Talk fast Australian accent Large area to explain Questions, Slow down

“ The fundamental problem with program maintenance is that fixing a defect has a substantial (20-50 %) chance of introducing another defect.” Mythical Man Month

Today: Test Driven Development

Test Driven Development History

Toyota Production System by Taiichi Ohno Competing with US companies was difficult. Smaller production runs of more models Waste when production runs finished and there were left over parts Ohno reverse engineered the production line and created “Just in time” manufacturing

Ohno reverse engineered the production line and created “Just in time” manufacturing

How is making cars anything like making software ? Complex processes Unable to be “explained” to the layman Like Ohno, we have waste Time Money Energy

Complex processes

Unable to be “explained” to the layman

Like Ohno, we have waste

Time

Money

Energy

Traditional model: Implementation Requirements Design Verification Maintenance

Unsurprisingly... As a programmer, you will be caught in the waterfall model. Your manager/your client will have provided the specs, and you now need to “follow the process” You are a cog in the machine.

As a programmer, you will be caught in the waterfall model.

Your manager/your client will have provided the specs, and you now need to “follow the process”

You are a cog in the machine.

Manufacturing & construction industries Software has requirements that are never in spec. Requirements evolve over time Software developers are rarely domain experts BDUF meant changes later on were costly Waterfall model is based on “Physical Design”

Manufacturing & construction industries BDUF meant changes later on were costly Software is difficult to change in maintenance Two teams same project.

How do you do it ?

The rules of fight club. 1. Write new code only if an automated test has failed. 2. Eliminate duplication.

1. Write new code only if an automated test has failed.

2. Eliminate duplication.

“ These are two simple rules, but they generate complex individual and group behavior with technical implications” Kent Beck

Unsurprisingly... As a programmer, you will be caught in the waterfall model. Your manager/your client will have provided the specs, and you now need to “follow the process” You are a cog in the machine.

As a programmer, you will be caught in the waterfall model.

Your manager/your client will have provided the specs, and you now need to “follow the process”

You are a cog in the machine.

FAIL FAIL Writing massive amounts of tests up front is “time expensive”, so with a goal in mind you can follow this flow chart. (Everyone loves flow charts) Add a test Run the tests Change Run the tests

Tests shouldn't take long to write. Tests shouldn't take long to run. The drive the “development” of the application. Write what it takes to make the test pass, and that is all. YNGNIA

Live programming demo

Useful URLs: android-sdk/platforms/android-1.5/samples/ApiDemos My life with android (mylifewithandroid.blogspot.com) Diego Torres Milano's blog (dtmilano.blogspot.com)

“ The fundamental problem with program maintenance is that fixing a defect has a substantial (20-50 %) chance of introducing another defect.” Mythical Man Month

CodeAndroid.org Android Developer/User Group Grassroots effort by developers Promote Android development around this region (SEA, Oceania) You can join us on Facebook, Twitter (codeandroid), IRC (#codeandroid @ irc.freenode.net) Special thanks to Google for the venue and food.

Android Developer/User Group

Grassroots effort by developers

Promote Android development around this region (SEA, Oceania)

You can join us on Facebook, Twitter (codeandroid), IRC (#codeandroid @ irc.freenode.net)