Keep a list of :next spec files in a file instead of keeping in spec/truffleruby.mspec

Author: andrykonchin

doc/contributor/workflow.md

@@ -306,8 +306,8 @@ PRETEND_RUBY_VERSION=3.2.0 jt test spec/ruby/.../some_spec.rb
 This also works for `jt tag`/`jt untag`.
 
 When working on a feature from the next version of Ruby, add the spec file in
-the corresponding file list (`:next`) in `spec/truffleruby.mspec` so that the
-specs are run in CI too.
+the corresponding files list in `spec/truffleruby.next-specs` so that the specs
+are run in CI too.
 
 ## How to fix a failing MRI test
 

spec/truffleruby.mspec

@@ -101,11 +101,13 @@ class MSpecScript
     "spec/truffle/capi"
   ]
 
-  # Use spec/ruby/core/nil/nil_spec.rb as a dummy file to avoid being empty
-  set :next, %w[
-    spec/ruby/core/nil/nil_spec.rb
-    spec/ruby/core/hash/shift_spec.rb
-  ]
+  # Use spec/truffleruby.next-specs to specify spec files to run for the next version.
+  # Allow comments and empty lines.
+  next_spec_files = File.readlines("spec/truffleruby.next-specs")
+                        .map(&:strip)
+                        .reject { |path| path.start_with?("#") || path.empty?  }
+
+  set :next, next_spec_files
 
   set :tags_patterns, [
     [%r(^(.*)/spec/ruby/(\w+)/(.+)_spec\.rb$), '\1/spec/tags/\2/\3_tags.txt'],

spec/truffleruby.next-specs

@@ -0,0 +1,12 @@
+# This file contains a list of spec files that contain specs for already
+# implemented features of the next CRuby release.
+#
+# These specs should be run as a separate step with `jt test :next` command
+# until TruffleRuby supports this next CRuby version.
+#
+# Empty lines and comments are allowed.
+
+# Use spec/ruby/core/nil/nil_spec.rb as a dummy file to avoid being empty (what causes mspec to error)
+spec/ruby/core/nil/nil_spec.rb
+
+spec/ruby/core/hash/shift_spec.rb