Add spec for use of :base in Dir#glob and tag it

[wildmaples]

Issue

We found this exception because it broke the TruffleRuby CI on SFR.

puts RUBY_DESCRIPTION
puts Dir.glob('**/*.rake', base: '.')

➜  storefront-renderer git:(master) ✗ ruby foo.rb
truffleruby 21.2.0-dev-d2532c21, like ruby 2.7.3, GraalVM CE JVM [x86_64-darwin]
<internal:core> core/dir_glob.rb:305:in `match?': undefined method `end_with?' for nil:NilClass (NoMethodError)
	from <internal:core> core/dir_glob.rb:286:in `process_entry'
	from <internal:core> core/dir_glob.rb:184:in `process_directory'
	from <internal:core> core/dir_glob.rb:413:in `run'
	from <internal:core> core/dir_glob.rb:466:in `glob'
	from <internal:core> core/dir.rb:250:in `block in glob'
	from <internal:core> core/dir.rb:247:in `each'
	from <internal:core> core/dir.rb:247:in `glob'
	from foo.rb:2:in `<main>'

TL;DR: If there are no path entries and the entry type is EndsWithEntryMatch, a nil class error will occur with the #end_with?(suffix) check.

I did some digging and it seems like there is no issue if Dir#glob is run without a base: Dir.glob('**/*.rake'). The code path diverges at this line when there is no glob_base_dir specified. In the problematic case, the @next is EndsWithEntryMatch, and when this Entry type is processed with no entry, there is a NilClass exception on #end_with?

Change

This change is just the test case that covers the issue. It passes on Ruby 2.7.3 and returns the exception (as seen above) on TrufleRuby.

Question

I don't have a lot of new context on the new Dir#glob changes, but this issue has something to do with the recent changes.

I have a branch here at gets rid of the exception but it does not pass the spec I added because the resulting array includes the file path of the mismatched directory.

Any idea to what the issue may be?

[eregon]

@aardvark179 has an upcoming fix for this, unfortunately it did not get merged yet due to some transient timeout:
master...eregon:gr-32025
We noticed the failure with https://github.com/eregon/truffleruby-gem-tracker, we should have told you about it since it would be likely you hit it too, sorry about that.

Thank you for the spec, more specs is always good :)