An Introduction to Agile Engineering Practices

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Kane Mar

“The New New Product Development Game”

- Takeuchi and Nonaka

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photo: http://www.flickr.com/photos/nicmcphee/

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From: Kent BeckTo: Jeff Sutherland <jsutherland>Reply: 70761.1216@compuserve.comDate: Mon, 15 May 1995 18:01:15 -0400 (EDT)Subj: HBR paper

_________________________ Is there a good place to get reprints of the SCRUM paper from

HBR? I've written patterns for something very similar and I want to make sure I steal as many ideas as possible.

Kent

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Continuous Integration

What is Continuous Integration?

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“Continuous Integration is a software development practice where members of a

team integrate their work frequently, usually each person integrates at least daily - leading to multiple integrations per day.

Each integration is verified by an automated build (including test) to detect integration errors as quickly as possible.”

-Martin Fowler

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Commit

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1. Compile & Build2. Unit Tests3. Integration Tests4. Report Errors

Commit

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1. Compile & Build2. Unit Tests3. Integration Tests4. Report Errors

Commit

Checkout

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1. Compile & Build2. Unit Tests3. Integration Tests4. Report Errors

Commit

Checkout

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1. Compile & Build2. Unit Tests3. Integration Tests4. Report Errors

Commit

Checkout

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Why is Continuous Integration important?

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1. Reducing Risk.

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When we are integrating the product all the time the risk of a

failed integration is spread throughout the duration of the

project ...

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rather than being left until the end.

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2. Behavior.

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If doing a complete build and test of any product is difficult ...

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doing it “continuously” is very difficult.

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Teams need to develop different

ways of working.

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Never letting the build break.

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1. Compile & Build2. Unit Tests3. Integration Tests4. Report Errors

Commit

CheckoutA broken build or integration test here ...

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1. Compile & Build2. Unit Tests3. Integration Tests4. Report Errors

Commit

CheckoutA broken build or integration test here ...

will get propagated here, here and here.

The Friday Afternoon Pattern of broken builds.

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Delivering smaller increments of well tested functionality.

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Investing in automated testing frameworks.

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Test, Test and Test again.

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I believe that all teams should practice CI.

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The tools are free, like free beer.

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The only price to pay for introducing CI is ...

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education.

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✦ http://www.martinfowler.com/articles/continuousIntegration.html

✦ http://cruisecontrol.sourceforge.net/✦ http://www.jetbrains.com/teamcity/✦ http://luntbuild.javaforge.com/✦ https://hudson.dev.java.net/

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References

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Test Driven Development

What is Test Driven Development?

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1. Add a test

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2. Run all test and see the new ones fail

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3. Write some code

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4. Run the automated tests and see them succeed

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5. Refactor

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Red/Green/Refactor

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Why is TDD important?

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TDD is a method of designing software, not merely an

approach to testing.

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“We found that test-first students on average wrote more tests and, in turn, students who wrote more tests tended to be

more productive.”- Erdogmus, Hakan; Morisio,

Torchiano45

Over a period of time, TDD will lead to suite of automated

integration tests.

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✦ Erdogmus, Hakan; Morisio, Torchiano. “On the Effectiveness of Test-first Approach to Programming,” Proceedings of the IEEE Transactions on Software Engineering, 31(1). January 2005. (NRC 47445). “We found that test-first students on average wrote more tests and, in turn, students who wrote more tests tended to be more productive.”

✦ Newkirk, JW and Vorontsov, AA. “Test-Driven Development in Microsoft .NET,” Microsoft Press, 2004.

✦ Feathers, M. “Working Effectively with Legacy Code,” Prentice Hall, 2004

✦ Beck, K. “Test-Driven Development by Example,” Addison Wesley, 2003

✦ Muller, Matthias M.; Padberg, Frank. “About the Return on Investment of Test-Driven Development (PDF)” Universitat Karlsruhe, Germany

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References

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Refactoring

What is Refactoring?

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“Refactoring is a disciplined technique for restructuring an existing body of code, altering its internal structure without

changing its external behavior.”- Martin Fowler

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“Each transformation (called a 'refactoring') does little, but a sequence of

transformations can produce a significant restructuring.”

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double disabilityAmount() { if (_seniority < 2) return 0; if (_monthsDisabled > 12) return 0; if (_isPartTime) return 0; // compute the disability amount

double disabilityAmount() { if (isNotEligableForDisability()) return 0; // compute the disability amount

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“Refactoring is a disciplined technique for restructuring an existing body of code, altering its internal structure without

changing its external behavior.”- Martin Fowler

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How do we establish that the behavior is unchanged?

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Continuous Integrationand

Test Driven Development

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The term Refactoring is poorly used.

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“If somebody talks about a system being broken for a

couple of days while they are refactoring ...”

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“you can be pretty sure they are not refactoring ... “

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“Refactoring is a very specific technique, founded on using

small behavior-preserving transformations”- Martin Fowler

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✦ Fowler, Martin (1999). “Refactoring.” Addison-Wesley. ISBN 0-201-48567-2.

✦ http://martinfowler.com/bliki/RefactoringMalapropism.html

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References

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Pair Programming

What is Pair Programming?

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Two team members working on the same code base and working

side-by-side

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photo: http://www.flickr.com/photos/improveit/

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“I told you Slashdot was more popular than Digg”

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Modern software development is full of drama ...

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photo: http://www.flickr.com/photos/improveit/

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photo: http://www.flickr.com/photos/improveit/

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The thrill of victory ...

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And the agony of defeat.

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Why is Pair Programming important?

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Pair Programming significantly reduces the number of defects, and greatly increase the quality

of the code.

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It is, however, very difficult to introduce.

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There are many issues mostly related to loss of personal space

and lack of privacy.

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Why do we care?

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80% of the cost of software is incurred after it has gone live.

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What would it mean to you if your cost of change was linear

rather than exponential?

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Thank You!

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