1.8 Compatibility via TracePoint

[trans]

I believe I can give you 1.8 compatibility, and in fact compatibility with any ruby engine that supports #set_trace_func.

A long time ago I wrote a tool called TracePoint. It should be pretty trivial to provide a result from it that exactly mimics Coverage.result. Would that do the trick? If so I will write it for you.

[colszowka]

That is exactly what would be required :)

Please go ahead if you think you can build something that returns a Coverage.result compatible with 1.9.x, that'd be awesome!

[trans]

Okay, preliminary work on this is here:

https://github.com/rubyworks/tracepoint/blob/master/lib/tracepoint/coverage.rb

It's not 100% exact to 1.9's Coverage library but it looks like it will be close enough. Here is an example of coverage for foo.rb in tracepiont's try/ directory:

tracepoint:  [nil, nil, 2, 1, nil, nil, 2, nil, nil, nil, 1]
ruby 1.9  :  [nil, nil, 1, 1, nil, nil, 1, 0, nil, nil, 1, nil]

The difference being that tracepoint counted one line twice, and does not include trailing blank lines.

The bigger issue though, is that I have not figured out a way to exclude files that aren't relevant from the coverage results b/c $LOADED_FEATURES in Ruby 1.8 doesn't use absolute paths. Any ideas?

[colszowka]

Pretty awesome! Did you try to do File.expand_path on the $LOADED_FEATURES array?

[trans]

Unfortunately File.expand_path won't work b/c that would make the path relative to the current working directory rather than the lib directories from which they are actually found.

I could match against the end of the path, that would probably work fine most of the time, but on occasion a false positive could creep in.

[colszowka]

Closing since basic compatibilty seems to be hard to achieve, nothing has happend on this for a while and also Ruby 1.8 is on the way out (official support even stops soon) and has a decent coverage lib in RCov, I don't think this is a subject worthwile of further keeping around. Please update if there are objections to this, and thanks for trying to make this work!

[trans]

Yep, I agree. 1.8 is finally about done.

Ironically it was thanks to this endeavor that I discovered Ruby 1.9's #set_trace_func is broken. And from conversation on core it sounds like no one plans to fix it. Rather the vibe I got was that #set_trace_func itself is on the way out. That being the case TracePoint has no means for working beyond 1.8 :-(

So it's a good thing I tried any way. C'est la vie.