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rcov is a code coverage tool for Ruby. It is commonly used for viewing overall
test coverage of target code. It features:
* fast execution: 20-300 times faster than previous tools
* multiple analysis modes: standard, bogo-profile, "intentional testing",
dependency analysis...
* detection of uncovered code introduced since the last run ("differential
code coverage")
* fairly accurate coverage information through code linkage inference using
simple heuristics
* cross-referenced XHTML and several kinds of text reports
* support for easy automation with Rake
* colorblind-friendliness
How do I use it?
In the common scenario, your tests are under test/ and the target code
(whose coverage you want) is in lib/. In that case, all you have to do is
use rcov to run the tests (instead of testrb), and a number of XHTML files
with the code coverage information will be generated, e.g.
rcov -Ilib test/*.rb
will execute all the .rb files under test/ and generate the code coverage
report for the target code (i.e. for the files in lib/) under coverage/. The
target code needs not be under lib/; rcov will detect is as long as it is
require()d by the tests. rcov is smart enough to ignore "uninteresting"
files: the tests themselves, files installed in Ruby's standard locations,
etc. See rcov --help for the list of regexps rcov matches filenames
rcov can also be used from Rake; see readme_for_rake or the RDoc documentation
for more information.
rcov can output information in several formats, and perform different kinds
of analyses in addition to plain code coverage. See rcov --help for a
description of the available options.
Sample output
The text report (also used by default in RcovTasks) resembles
| File | Lines | LOC | COV |
|lib/rcov.rb | 572 | 358 | 91.3% |
|Total | 572 | 358 | 91.3% |
91.3% 1 file(s) 572 Lines 358 LOC
The (undecorated) textual output with execution count information looks like this:
$ rcov --no-html --text-counts b.rb
| 2
a, b, c = (1..3).to_a | 2
10.times do | 1
a += 1 | 10
20.times do |i| | 10
b += i | 200
b.times do | 200
c += (j = (b-a).abs) > 0 ? j : 0 | 738800
end | 0
end | 0
end | 0
rcov can detect when you've added code that was not covered by your unit
$ rcov --text-coverage-diff --no-color test/*.rb
Finished in 1.163085 seconds.
39 tests, 415 assertions, 0 failures, 0 errors
!!!!! Uncovered code introduced in lib/rcov.rb
### lib/rcov.rb:207
def precompute_coverage(comments_run_by_default = true)
changed = false
lastidx = lines.size - 1
if (!is_code?(lastidx) || /^__END__$/ =~ @lines[-1]) && !@coverage[lastidx]
!! # mark the last block of comments
!! @coverage[lastidx] ||= :inferred
!! (lastidx-1).downto(0) do |i|
!! break if is_code?(i)
!! @coverage[i] ||= :inferred
!! end
!! end
(0...lines.size).each do |i|
next if @coverage[i]
line = @lines[i]
rcov is released under the terms of Ruby's license.
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