MetricAdapter

At LiquidPlanner, we wanted to build some tools to help us analyze our code. There are a ton of static analyzers for ruby, each providing different insightful metrics, so there's no need to write a new analyzer. But what do you do when you want to use more than one of them?

Each analyzer takes a different configuration, and provides results in different formats. MetricAdapter solves the latter problem by converting the results of each analyzer into a common format.

Now you can take all of these wonderful libraries and combine their results without worrying about how they internally represent their metrics.

Each metric represents a single statement about one line of code. Flay for instance, generates reports that looks like this:

1) IDENTICAL code found in :lasgn (mass*2 = 24)
  lib/adapters/flay_adapter.rb:26
  lib/adapters/flog_adapter.rb:23

In this case, two metrics would be generated, one per line. This makes it easier to annotate source files, or integrate these libraries with your favorite editor (sed, I kid, I know we all use notepad these days).

Each metric contains:

• Metric#location – An object representing a file path and line number
• Metric#signature – The associated method signature (not all metrics currently have this)
• Metric#message – A message explaining the metric, for instance "Has no descriptive comment"
• Metric#score – When applicable, a numeric score or rating indicating the severity

To get normalized metrics, instantiate the static analysis library of your choice, and pass it to the appropriate adapter:

# Instantiate and configure your analyzer
flay = Flay.new :mass => 4 
flay.process(*files)
flay.analyze

# Report on the adapted metrics
adapter = MetricAdapter::FlayAdapter.new(flay)
adapter.metrics.each do |m|
  puts "#{m.location} - #{m.message}"
end

For a full example, see examples/report.rb and examples/annotate.rb. You can use these examples to build tools that are appropriate for your team.

• Flay – Code duplication
• Flog – Code complexity
• Reek – Code smells

Please do! Take a look at the existing adapters and tests (lib/adapters and test/*_adapter_test.rb) for examples.

Adam Sanderson for LiquidPlanner