[ruby-core:84860] [Ruby trunk Bug#9572] Restarting Coverage does not produce correct coverage result

Issue #9572 has been updated by tenderlovemaking (Aaron Patterson).

Backport deleted (1.9.3: UNKNOWN, 2.0.0: UNKNOWN, 2.1: UNKNOWN)

I have two questions:

1. How is this different than recording the current coverage with `peek_result`, then subtracting later?  Like this for example: https://gist.github.com/tenderlove/eefcce7dcadb0ed48968f575698e3f04

2. Is there a reason you need to call `Coverage` methods from within files whose coverage is being measured?  It seem strange for an observation tool to be observing itself.

I really don't like the idea of mutating a global (the coverage information).  I can't say I fully understand the problem you're trying to solve, but it seems like being able to record coverage information at any time, then being able to calculate differences would be flexible enough to deal with any coverage situation you need.

----------------------------------------
Bug #9572: Restarting Coverage does not produce correct coverage result
https://bugs.ruby-lang.org/issues/9572#change-69574

* Author: sean_ferguson (Sean Ferguson)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: ruby 2.6.0dev (2018-01-13 trunk 61811) [x86_64-darwin15]
* Backport: 
----------------------------------------
Feature 4796(https://www.ruby-forum.com/topic/1811306#1001864) appears
to have a bug in it.

While the test listed there does pass the following test does not:
<pre>
require "test/unit"
require "coverage"
require 'tmpdir'
class TestCoverage < Test::Unit::TestCase
  def test_restarting_coverage
    Dir.mktmpdir {|tmp|
      Dir.chdir(tmp) {
        File.open("test.rb", "w") do |f|
          f.puts <<-EOS
            def coverage_test_method
              puts :ok
            end
          EOS
        end
        Coverage.start
        require tmp + '/test.rb'
        Coverage.result
        Coverage.start
        coverage_test_method
        result = Coverage.result
        assert_equal 1, result.size
        assert_equal [0, 1, nil], result.first[1] # coverage stats show an empty array here
      }
    }
  end
end
</pre>
It appears that while the coverage is finding the correct files it is
not giving any coverage stats for those files. Knowing this information would be very helpful in determining test coverage data for individual test files. I'm not very familiar
with how the coverage library works, but if you can point me at where to
look I can give fixing it a try.

Thanks,

Sean Ferguson



-- 
https://bugs.ruby-lang.org/

Unsubscribe: <mailto:[e-mail]?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>