This document discusses code quality tools for Ruby code and how RubyMine can help. It introduces static and runtime tools for finding code smells, metrics for measuring qualities like duplication, and testing and coverage tools. RubyMine integrates many of these tools and performs on-the-fly code inspections to help improve code quality. The document encourages attendees to try RubyMine's code quality features themselves.

1. Fighting Code Smell
with RubyMine
Dennis Ushakov
Oleg Shpynov
www.jetbrains.com

2. Goals of this workshop
• Show available code quality tools
• How do they work
• Show what RubyMine can offer
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3. Working with code
20%
Write new code
80%
Modify existing
code: bugfixes,
optimizations,
etc.
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4. Code quality tools
Reek
Flay Flog
Roodi Dust Heckle
Metrics_fu
RSpec Cucumber Autotest
RCov SimpleCov
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5. Code quality tools
• Static
• Runtime
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6. 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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7. 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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8. 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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9. 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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10. 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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11. 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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12. Practice
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13. 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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14. 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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15. GO AND TRY!
jetbrains.com/ruby
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16. 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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17. Develop with pleasure!
Dennis.Ushakov@jetbrains.com @en_dal
Oleg.Shpynov@jetbrains.com @oleg_s
www.jetbrains.com
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