Fighting Ruby code smell

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Fighting Code Smell

with RubyMine

Dennis Ushakov

Oleg Shpynov

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Goals of this workshop

• Show available code quality tools

• How do they work

• Show what RubyMine can offer

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Working with code

20%

Write new code

80% Modify existing

code: bugfixes,

optimizations,

etc.

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Code quality tools

Reek

Flay Flog

Roodi Dust Heckle

Metrics_fu

RSpec Cucumber Autotest

RCov SimpleCov

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Code quality tools

• Static

• Runtime

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Static tools

• Inspect your code without launching it

•100% side effects free

•Easy to use

•Challenging to implement

•Rails DSL magic kills ‘em

•Ruby has no formal specification

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Runtime tools

• Inspect your code by launching it

•100% follow the way Ruby works

•Cope well with Rails DSL

•MAY have side effects

•Works until the very first failure

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Code that smells

• Runtime errors

• Runtime warnings (like parens in calls etc.)

• Dead code

• Copy/paste

• Complex method bodies

• Code style violations (i.e. naming conventions, etc)

• Framework pattern violations (MVC pattern violations)

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Metrics

• Reek

– Uncommunicative name

– One char name

– Name ends with number

– Camelcase variable

– instance_of?, kind_of?, is_a? instead of polymorphism

– Duplication

– Long class, method, parameter list

– Nested iterators

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Metrics

• Flog

– Assignment Branch Call metrics

• Saikuro

– Cyclomatic complexity

• Roodi

– Assignment in condition

– Missing else in case

– Long class/module/method

– Class/module/method name check

– Cyclomatic complexity

• Flay

– Duplicates

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Testing and Coverage tools

• RSpec

• Cucumber

• Autotest

• RCov, SimpleCov

• Continuous integration

• Heckle

– Change code (if <-> unless, calls, numbers, assignments, etc.) to see if test fail

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Practice

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What else can be done?

All these tools use Abstract Syntax Tree, but this is not all the information that can be extracted!

The main problem is Ruby object model complexity

LEXICAL analysis

• Lexer -> Parser -> Abstract Syntax Tree -> Control Flow Graph -> Data Flow Analysis

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RubyMine

• On the fly code inspections

• Code duplicates

• Test tools integration with graphical UI

• Coverage tool integration

• Everything is tightly integrated in IDE

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GO AND TRY!

jetbrains.com/ruby

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Thank you!

• Visit us http://www.jetbrains.com/ruby

• Read about http://blogs.jetbrains.com/ruby/

• Post bugs http://youtrack.jetbrains.net/issues/RUBY

• Follow us on twitter @rubymine

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Develop with pleasure!

[email protected] @en_dal

[email protected] @oleg_s

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