Testing in Legacy: From Rags to Riches

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I’d like to share our experience

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About me

{ “First name”: “Taras”, “Last name”: “Slipets”, “E-mail”: “taras.slipets@gmail.com”, “LinkedIn Profile”: “http://www.linkedin.com/ pub/taras-slipets/ 48/466/516”, “Interests”: [ “Software Engineering”, “Music”, “Skiing”, ]}

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About presentation

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About presentation

• General feeling about legacy

• System that we’ve received for improvement

• Effective steps that were performed

• What we’ve eventually reached

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What does it mean – Legacy system?

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Ask expert

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Legacy system is…

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Just long-term project

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Where do we go now

• General feeling about legacy

• System that we’ve received for improvement

• Effective steps that were performed

• What we’ve eventually reached

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What we’ve received

• 11-years old system SUCCESSFULLY running on production servers• Written in Java 1.4• No frameworks usage• No documentation• No developers who has worked on it• Impatient customers• Pantient management• other surprises…

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Bus factor

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What we’d like to have?

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What we’d like to have?

Shiny system with all cutting-edge frameworks

Reduce pain of maintenance and support

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What we’d like to have?

Shiny system with all cutting-edge frameworks

Reduce pain of maintenance and support

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Where do we go now

• General feeling about legacy

• System that we’ve received for improvement

• Effective steps that were performed

• What we’ve eventually reached

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So, how we did it?

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Setup your environmentLet’s deployour changes!

Great! Wheredo we go?

Directly to production!

“To production!”he said…

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Setup your environment

DEV STAGE PROD

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Logs, logs, logs

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Domain model – classes level

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Domain model – database level

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Domain model – workflows

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Peer review VERY often

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Before changing code

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We need to ensure it works

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Testing

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Testing levels

Unit testsIntegration testsSystem tests

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Test existing and expected behavior

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System testing (feature testing)

Application under testingSystem tests

Process Process

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External world communication

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External world communication - mocks

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External world communication - mocks

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External world communication - mocks

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External world communication - mocks

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System tests automation

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Finally – let’s touch code!

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Top occurring issues

• “do-stuff” methods• “I’m aware of everything” classes• “Celebrities” classes/interfaces• “Magic goes here” blocks without comments• Just obsolete code

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What to do?

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How about

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Refactoring facilities• Extract method• Extract interface• Parameter object• Method object• Replace type-checking code with

State/Strategy• Move method/field• …

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Unit tests jumps into

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Frameworks

• EasyMock

• Mockito

• PowerMock

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IndicationAfter initial tests are written, use PowerMock as indicator of bad system design

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What is next?

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Most used in our case

• Template method• Strategy• State• Visitor• Command• Chain of Responsibility• Observer

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And again - logs, logs, logs

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Hey, where are new features?

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Extend functionality AFA it’s possible

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How deep refactoring should be?

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Theory the Godmother

• S.O.L.I.D.

• D.R.Y.

• K.I.S.S.

• …

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In real world

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Now we can add integration tests

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What about build/deployment time?

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What about build/deployment time?

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Simple rule

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But for us it hurt

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Remedy?

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Remedy

• Make app self-contained

• Simplify manual installation

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Operations are happy

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If it steal hurts - automate deployment

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Where do we go now

• General feeling about legacy

• System that we’ve received for improvement

• Effective steps that were performed

• What we’ve eventually reached

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Complete features list + tests for them

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The winner takes it all

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The dreams come true - build-pipeline!

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A-team!

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Lessons learned

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Lessons learned

• Old project is not a disaster, but challenge• Start from environment setup and feature testing. At least to

some extent• Share knowledge with your colleagues and write docs• Do not underestimate power of classical remedies (patterns,

working techniques)• Be agile ;)

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Links

• http://www.amazon.com/Working-Effectively-Legacy-Michael-Feathers/dp/0131177052

• http://xpdays.com.ua/archive/xp-days-ukraine-2011/materials/legacy/

• http://xpdays.com.ua/archive/xp-days-ukraine-2012/materials/code-story/

• http://jeeconf.com/archive/materials-2014/legacy-projects/• http://jeeconf.com/materials/web-application-i-have-always-drea

mt-of/

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Thanks for your attention!