Jruby Coverage Differences

dog.rb

# frozen_string_literal: true

class Dog
  def bark
    'woof'
  end
end

jruby_test.rb

# This is all related to trying to get Coverband to work for Jruby apps
# see https://github.com/danmayer/coverband/issues/361
require 'coverage'

Coverage.start

require './dog.rb'

puts Coverage.peek_result
puts "done"

output on MRI

bundle exec ruby test/jruby_check.rb
{"/Users/danmayer/projects/coverband/test/dog.rb"=>[nil, nil, 1, 1, 0, nil, nil]}

output with JRuby

bundle exec ruby test/jruby_check.rb
test/jruby_check.rb:3: warning: tracing (e.g. set_trace_func) will not capture all events without --debug flag
{"/Users/danmayer/projects/coverband/test/dog.rb"=>[nil, nil, 0, 0, 0, nil, nil]}

> The above does not match MRI, becasue there are 0's where I would expect hits for parsing the methods...

bundle exec ruby --debug test/jruby_check.rb
{"/Users/danmayer/projects/coverband/test/dog.rb"=>[nil, nil, 1, 1, 0, nil, nil]}

> Now this matches, I can also get matching output with a `.jrubyrc` setting `debug.fullTrace=true`

ruby --version
jruby 9.2.9.0 (2.5.7) 2019-10-30 458ad3e OpenJDK 64-Bit Server VM 13.0.1+9 on 13.0.1+9 +jit [darwin-x86_64]