Fix backtrace filtering

[djanowski]

And make it work with e.g. gemsets.

This works: https://gist.github.com/djanowski/afed5a759687921f0569

[britishtea]

Won't $LOAD_PATH often include the files that your code under test is stored in? If that's the case, you'll often end up with an empty stack trace.

[djanowski]

Not if you require this file before anything else, which is the most common use case, right?

[britishtea]

That's true (though I know of at least one project where I'd end up with empty backtraces 😊).

Perhaps this is a good use case for Ruby's awk inheritance: BEGIN { $ORIGINAL_LOAD_PATH = $LOAD_PATH.dup }.

[djanowski]

The constant is created when the module is required, and the array is the result of adding Gem.path to $LOAD_PATH. So further modifications to $LOAD_PATH won't be a problem. Is that what you mean?

[britishtea]

Yes.

Consider the / my typical Rakefile:

$LOAD_PATH.unshift File.expand_path("./lib")

require "cutest" # or require "test_helper"
require "my_library"

task(:foo) { MyLibrary.do_something! }
task(:bar) { MyLibrary.do_something_else! }
task(:test) { Cutest.run(FileList["test/*_test.rb"]) }

In such cases you'd end up with an empty backtrace and it will not be obvious why. Capturing the $LOAD_PATH in a BEGIN block avoids this at least partially: it will execute before anything else does.

Another situation where you'd end up with an empty backtrace is running a single test file using ruby -I lib test/my_library_test.rb. A BEGIN block won't avoid this, unfortunately.

[djanowski]

Yes, it's true, this is opinionated based on the fact that I never include my application's directories in $LOAD_PATH. I always use require for libraries, require_relative for code inside my app.

Maybe just using Gem.path is enough.