Update: Starting from JSCover version 1.05 the hacks I outlined in my previous answer are no longer needed. I've updated my answer to reflect this.
I managed to get JSCover working in the Rails + Capybara pipeline, but it did take some hacking to get it to work. I built a little rake task that:
- uses the rails asset pipeline to generate the scripts
- calls the java jar to instrument all the files and generate an empty report into a temp dir
- patches the jscover.js script to operate in "report mode" (simply add jscoverage_isReport=true at the end)
- copies the result to /public/assets so the tests pick it up without needing any changes and so the coverage report can be opened automatically in the browser
Then I added a setup task to clear out the browser's localStorage at the start of the tests and a teardown task that writes out the completed report at the end.
def setup
unless $startup_once
$startup_once=true
puts 'Clearing localStorage'
visit('/')
page.execute_script('localStorage.removeItem("jscover");')
end
end
def teardown
out=page.evaluate_script("typeof(_$jscoverage)!='undefined' && jscoverage_serializeCoverageToJSON()")
unless out.blank? then
File.open(File.join(Rails.root,"public/assets/jscoverage.json"), 'w') {|f| f.write(out) }
end
end
Anyway, the end result works nicely, the advantage of doing it this way is that it also works on headless browsers so it can also be included in CI.
*** Update 2: Here is a rake task that automates the steps, drop this in /lib/tasks
# Coverage testing for JavaScript
#
# Usage:
# Download JSCover from: http://tntim96.github.io/JSCover/ and move it to
# ~/Applications/JSCover-1
# First instumentalize the javascript files:
# rake assets:coverage
# Then run browser tests
# rake test
# See the results in the browser
# http://localhost:3000/assets/jscoverage.html
# Don't forget to clean up instrumentalization afterwards:
# rake assets:clobber
# Also don't forget to re-do instrumentalization after changing a JS file
namespace :assets do
desc 'Instrument all the assets named in config.assets.precompile'
task :coverage do
Rake::Task["assets:coverage:primary"].execute
end
namespace :coverage do
def jscoverage_loc;Dir.home+'/Applications/JSCover-1/';end
def internal_instrumentalize
config = Rails.application.config
target=File.join(Rails.public_path,config.assets.prefix)
environment = Sprockets::Environment.new
environment.append_path 'app/assets/javascripts'
`rm -rf #{tmp=File.join(Rails.root,'tmp','jscover')}`
`mkdir #{tmp}`
`rm -rf #{target}`
`mkdir #{target}`
print 'Generating assets'
require File.join(Rails.root,'config','initializers','assets.rb')
(%w{application.js}+config.assets.precompile.select{|f| f.is_a?(String) && f =~ /\.js$/}).each do |f|
print '.';File.open(File.join(target,f), 'w') {|ff| ff.write(environment[f].to_s) }
end
puts "\nInstrumentalizing…"
`java -Dfile.encoding=UTF-8 -jar #{jscoverage_loc}target/dist/JSCover-all.jar -fs #{target} #{tmp} #{'--no-branch' unless ENV['C1']} --local-storage`
puts 'Copying into place…'
`cp -R #{tmp}/ #{target}`
`rm -rf #{tmp}`
File.open("#{target}/jscoverage.js",'a'){|f| f.puts 'jscoverage_isReport = true' }
end
task :primary => %w(assets:environment) do
unless Dir.exist?(jscoverage_loc)
abort "Cannot find JSCover! Download from: http://tntim96.github.io/JSCover/ and put in #{jscoverage_loc}"
end
internal_instrumentalize
end
end
end
