CSC/ECE 517 Fall 2010/ch4 4h am

Static Analysis Tools for Ruby

Static analysis tools are used to create an interface between the program, analysis, and the user. These tools perform many different functions through simple commands. The results of the tools are shown in various ways; through graphs, underlines in code, pop-up text boxes, and many other possibilities. A downside to the use of static analysis tools is knowing whether or not the tool knows exactly what the coder intended. For example, a programmer may not care that the current piece of code is used in another section because it may be more important for it to be in two places, yet not important enough to become its own method.

Tools

There are a number of static analysis tools and code metrics tools that programmers use to sift through their code. The ones that appear to be most popular are described below.

Reek

"Reek v1.2.8 is a tool that examines Ruby classes, modules and methods and reports any Code Smells it finds." ^[1]

Code Smells

"Smells are indicators of where your code might be hard to read, maintain or evolve, rather than things that are specifically wrong. Naturally this means that Reek is looking towards your code’s future." ^[1] The following items describe the smells that Reek can find

• Attribute - attr, attr_reader, attr_writer, and attr_accessor raise a warning
• Class Variable - these variables are used globally and can break many places where the variable is used
• Control Couple - the most common type of control couple is a conditional statement that determines the path of execution
• Data Clump - this occurs when a group of items appear in the same fashion in classes, parameter lists, or when instance variables contain similar substrings
• Duplication - this occurs when code fragments are similar or perform similar tasks
• Irresponsible Module - these are classes and methods that do not have comments preceding them that describe the purpose
• Large Class - this is a class with a large number of variables, methods, or lines of code
• Long Method - a large number of lines of code
• Long Parameter List - a method with more than two or three parameters
• Low Cohesion
  • Feature Envy - the use of other class variables or methods more times than its own class items
  • Utility Function - a function that is never called within the class it is defined in, but is called within other classes
• Nested Iterators - a block of code that includes another block of code
• Simulated Polymorphism - case statements with different types in each case, comparisons using if statements of the same variable with different types, etc...
• Uncommunicative Name - names of variables, methods, or classes that don't make sense for what it is being used

Ruby Version Compliance

Reek v1.2.8 requires Ruby versions - 1.9.1, 1.8.7, or 1.8.6

Installing Reek

From the command line or in eclipse, type

 gem install reek 

Running Reek

From the command line or in eclipse, type

 reek [options] [dir_or_source_file]* 

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Saikuro

Saikuro version 0.3 is a cyclomatic complexity analyzer,^[2] which essentially counts the number of independent paths through the code.^[3] The higher the number that is returned the more complex the code. This means complex code "is more prone to error, harder to understand, harder to test, and harder to modify."^[3] The output of the program gives you the complexity number for the file that is tested. It will also tell you the number of tokens per line.

Ruby Version Compliance

Saikuro v0.3 does not list the required version; however it has been tested in 1.8.7 and 1.9.2 and it does not work. The v0.3 was released on June 21, 2008, which corresponds to Ruby version 1.8.6 (according to http://rubyforge.org/frs/?group_id=426)

Installing Saikuro

From the command line, type

 gem install Saikuro 

Running Saikuro

From the command line, type

saikuro -c -p dir/fileName.rb

The results are saved in the current directory.

For more information on running Saikuro, on the command line type

saikuro -h

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Roodi

Roodi, short for Ruby Object Oriented Design Inferometer, version 2.1.0 sifts through the passed code and performs various checks. The checks that are described below are verbatim from the Readme.txt file.^[4]

Checks

• AssignmentInConditionalCheck - Check for an assignment inside a conditional. It‘s probably a mistaken equality comparison.
• CaseMissingElseCheck - Check that case statements have an else statement so that all cases are covered.
• ClassLineCountCheck - Check that the number of lines in a class is below the threshold.
• ClassNameCheck - Check that class names match convention.
• CyclomaticComplexityBlockCheck - Check that the cyclomatic complexity of all blocks is below the threshold.
• CyclomaticComplexityMethodCheck - Check that the cyclomatic complexity of all methods is below the threshold.
• EmptyRescueBodyCheck - Check that there are no empty rescue blocks.
• ForLoopCheck - Check that for loops aren‘t used (Use Enumerable.each instead)
• MethodLineCountCheck - Check that the number of lines in a method is below the threshold.
• MethodNameCheck - Check that method names match convention.
• ModuleLineCountCheck - Check that the number of lines in a module is below the threshold.
• ModuleNameCheck - Check that module names match convention.
• ParameterNumberCheck - Check that the number of parameters on a method is below the threshold.

Ruby Version Compliance

Roodi v2.1.0 is compliant with Ruby v1.9 (Author's Blog)

Installing Roodi

From the command line

 gem install roodi 

Running Roodi

roodi "rails_app/**/*.rb"

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Flog

Here is what Flog can do

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Flay

Flay analyzes ruby code for structural similarities. Differences in literal values, names, whitespace and programming style are all ignored. By using Abstract Syntax Tree of ruby source, instead of ruby source code, it is possible to compare the code structurally. Copy/Pasted code can be detected even if literal values are modified. Flay uses ruby_parser to parse ruby code.

Ruby Version Compliance

Flay 1.4.1 is compliant with Ruby v1.8 (according to http://rubydoc.info/gems/flay/1.4.1/frames)

Installing Flay

From the command line

 gem install flay 

Running Flay

Run verbose to see an N-way diff of the code

flay -v ruby_code/*.rb

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Nitpick

Nitpick is intended to be a customizable static checked for Ruby. It currently consists of a script which scans required code using method_added and outputs various warnings. It also provides code level access to the warnings. Many things Nitpick can do, Ruby can warn about with -w option but that requires you to notice at runtime and many apps won't run clearly with -w option. The goal of Nitpick is to be able to inspect the code for what you care about before putting it in production.

Ruby Version Compliance

Nitpick 1.0.1 is compliant with Ruby v1.8

Installing Nitpick

gem install nitpick -v 1.0.1 

Running Nitpick

From the command line, type

 Nitpick ruby_source/*.rb 

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Rufus

Here is what Rufus can do

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Metric_fu

Here is what Metric_fu can do

Conclusion

Here it is

References

1. ^{a, b} Rutherford, K. (2010, April 26). Reek Wiki. Retrieved October 15, 2010, from Github: http://github.com/kevinrutherford/reek/wiki

2. Blut, Z. (n.d.). Saikuro:A Cyclomatic Complexity Analyzer. Retrieved October 15, 2010, from Rubyforge: http://saikuro.rubyforge.org

3. ^{a, b} Watson, A. H., & McCabe, T. J. (1996). Structured Testing: A Testing Methodology Using the Cyclomatic Complexity Metric. National Institute of Standards and Technology, Computer Systems Laboratory. Gaithersburg: National Institute of Standards and Technology.

4. Andrews, M. (n.d.). Roodi. Retrieved October 15, 2010, from Rubyforge: http://roodi.rubyforge.org

4. Ruby Sadists. (n.d.). Retrieved October 15, 2010, from Confessions of a Ruby Sadist: http://ruby.sadi.st

5. Clark, K. (n.d.). Nitpick Wiki. Retrieved October 15, 2010, from Github: http://github.com/kevinclark/nitpick/wiki

6. Schuster, W. (2008, November 07). Static Analysis Tools Roundup: Roodi, Rufus, Reek, Flay. Retrieved October 15, 2010, from InfoQ: http://www.infoq.com/news/2008/11/static-analysis-tool-roundup

7. Sidorov, D. (2009, June 29). Static Analysis for Ruby/Python. Retrieved October 13, 2010, from Klockwork: http://www.klocwork.com/blog/2009/06/static-analysis-for-rubypython/

8. Skruggs, J. (n.d.). Metric_fu. Retrieved October 15, 2010, from Rubyforge: http://metric-fu.rubyforge.org/