[ruby-core:116222] [Ruby master Bug#19857] Eval coverage is reset after each `eval`.

Issue #19857 has been updated by ioquatix (Samuel Williams).


> When I started developing the covearge library, I decided that its target is "source files that actually exist".

I completely agree with this and I don't think that statement has any bearing on this proposal.

> The measured coverage is visually observed by a human, which requires source code, and Ruby interpreter did not keep the eval'ed source code (at that time). I think that the design decision to target only source files was natural.

Makes sense.

> Because the Rails view code (.erb) exists as a file, I thought that it is the target of covearge library. So I accepted #19008.

That's reasonable.

> Beyond that, measuring coverage on dynamically generated code conflicts with the coverage library's initial design decision.

That's not what this PR is doing?

> To be honest, I don't want to further complicate the coverage library. Frankly, its API is already very complicated. I no longer want to expand it beyond the initial design decision.

This PR addresses a real world problem I ran into.

I accept the example given isn't clear. However, I'd like to discuss this at developer meeting.

----------------------------------------
Bug #19857: Eval coverage is reset after each `eval`.
https://bugs.ruby-lang.org/issues/19857#change-106243

* Author: ioquatix (Samuel Williams)
* Status: Rejected
* Priority: Normal
* Assignee: ioquatix (Samuel Williams)
* Backport: 3.0: DONTNEED, 3.1: DONTNEED, 3.2: REQUIRED
----------------------------------------
It seems like `eval` based coverage is reset every time eval is invoked.

```ruby
#!/usr/bin/env ruby

require 'coverage'

def measure(flag)
  c = Class.new
  c.class_eval(<<~RUBY, "foo.rb", 1)
    def foo(flag)
      if flag
        puts "foo"
      else
        puts "bar"
      end
    end
  RUBY
  
  return c.new.foo(flag)
end

Coverage.start(lines: true, eval: true)

# Depending on the order of these two operations, different coverage is calculated, because the evaluation of the code is considered different, even if the content/path is the same.
measure(false)
measure(true)

p Coverage.result
```

Further investigation is required.



-- 
https://bugs.ruby-lang.org/
 ______________________________________________
 ruby-core mailing list -- [e-mail]
 To unsubscribe send an email to [e-mail]
 ruby-core info -- https://ml.ruby-lang.org/mailman3/postorius/lists/ruby-core.ml.ruby-lang.org/