== Code coverage analysis automation with Rant

Since 0.5.0, <tt>rcov</tt> features a <tt>Rcov</tt> generator for eant
which can be used to automate test coverage analysis.  Basic usage is as
follows:

  require 'rcov/rant'
 
  desc "Create a cross-referenced code coverage report."
  gen Rcov do |g|
    g.test_files = sys['test/test*.rb']
  end

This will create by default a task named <tt>rcov</tt>.

=== Passing command line options to <tt>rcov</tt>

You can provide a description, change the name of the generated tasks (the
one used to generate the report(s) and the clobber_ one) and pass options to
<tt>rcov</tt>:

  desc "Create cross-referenced code coverage report."
  gen Rcov, :coverage do |g|
    g.test_files = sys['test/test*.rb']
    g.rcov_opts << "--threshold 80" << "--callsites"
  end

That will generate a <tt>coverage</tt> task.

You can specify a different destination directory, which comes handy if you
have several rcov tasks:

  desc "Analyze code coverage for the FileStatistics class."
  gen Rcov, :rcov_sourcefile do |g|
    g.libs << "ext/rcovrt"
    g.test_files = sys['test/test_FileStatistics.rb']
    g.rcov_opts << "--test-unit-only"
    g.output_dir = "coverage.sourcefile"
  end

  desc "Analyze code coverage for CodeCoverageAnalyzer."
  gen Rcov, :rcov_ccanalyzer do |g|
    g.libs << "ext/rcovrt"
    g.test_files = sys['test/test_CodeCoverageAnalyzer.rb']
    g.rcov_opts << "--test-unit-only"
    g.output_dir = "coverage.ccanalyzer"
  end

=== Options specified passed to the generator 

The +Rcov+ generator recognizes the following options:
+libs+:: directories to be added to the <tt>$LOAD_PATH</tt>
+rcov_opts+:: array of options to be passed to rcov
+test_files+:: files to execute
+test_dirs+:: directories where to look for test files automatically
+pattern+:: pattern for automatic discovery of unit tests to be executed
+output_dir+:: directory where to leave the generated reports

+test_files+ overrides the combination of +test_dirs+ and +pattern+.


=== Options passed through the <tt>rake</tt> command line

You can override the options defined in the Rcov tasks by specifying them 
using environment variables at the time rant is executed.
  RCOVPATH=/my/modified/rcov rant rcov       # use the specified rcov executable
  RCOVOPTS="--no-callsites -x foo" rant rcov # pass those options to rcov