[DRE-maint] Bug#888150: ruby-graphviz: FTBFS on ruby2.5: undefined method `graph' for nil

[Chris West (Faux)]

Source: ruby-graphviz
Version: 1.2.2-1
Severity: important
User: debian-ruby at lists.debian.org
Usertags: ruby2.5

Dear Maintainer,

This package fails to build against ruby2.5. Soon, there will
be a transition to ruby2.5, and this package will FTBFS in sid.

There may be some details on the wiki about common problems:
https://wiki.debian.org/Teams/Ruby/Ruby25Transition

Build log excerpt:


100 tests, 258 assertions, 0 failures, 0 errors, 0 pendings, 0 omissions, 0 notifications
100% passed
------
9.15 tests/s, 23.62 assertions/s
/usr/bin/ruby2.5 /usr/bin/gem2deb-test-runner

┌──────────────────────────────────────────────────────────────────────────────┐
│ Run tests for ruby2.5 from debian/ruby-tests.rake                            │
└──────────────────────────────────────────────────────────────────────────────┘

RUBYLIB=/build/ruby-graphviz-1.2.2/debian/ruby-graphviz/usr/lib/ruby/vendor_ruby:. GEM_PATH=debian/ruby-graphviz/usr/share/rubygems-integration/all:/root/.gem/ruby/2.5.0:/var/lib/gems/2.5.0:/usr/lib/x86_64-linux-gnu/rubygems-integration/2.5.0:/usr/share/rubygems-integration/2.5.0:/usr/share/rubygems-integration/all ruby2.5 -S rake -f debian/ruby-tests.rake
/usr/bin/ruby2.5 -w -I"test"  "/usr/lib/ruby/vendor_ruby/rake/rake_test_loader.rb" "test/output/dot/hello_test.rb" "test/output/dot/test_parse.rb" "test/output/rgv/test_rgv.rb" "test/test_dot_script.rb" "test/test_examples.rb" "test/test_graph.rb" "test/test_search.rb" "test/test_subgraph.rb" "test/test_theory.rb" "test/test_types.rb" "test/test_utils_colors.rb" -v
/build/ruby-graphviz-1.2.2/test/output/dot/hello_test.rb:6: warning: shadowing outer local variable - g
/build/ruby-graphviz-1.2.2/debian/ruby-graphviz/usr/lib/ruby/vendor_ruby/graphviz/dot2ruby.rb:51: warning: instance variable @_graph_eval not initialized
/build/ruby-graphviz-1.2.2/test/output/dot/hello_test.rb:18:in `<top (required)>': undefined method `graph' for nil:NilClass (NoMethodError)
	from /usr/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require'
	from /usr/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require'
	from /usr/lib/ruby/vendor_ruby/rake/rake_test_loader.rb:17:in `block in <main>'
	from /usr/lib/ruby/vendor_ruby/rake/rake_test_loader.rb:5:in `select'
	from /usr/lib/ruby/vendor_ruby/rake/rake_test_loader.rb:5:in `<main>'
rake aborted!
Command failed with status (1): [ruby -w -I"test"  "/usr/lib/ruby/vendor_ruby/rake/rake_test_loader.rb" "test/output/dot/hello_test.rb" "test/output/dot/test_parse.rb" "test/output/rgv/test_rgv.rb" "test/test_dot_script.rb" "test/test_examples.rb" "test/test_graph.rb" "test/test_search.rb" "test/test_subgraph.rb" "test/test_theory.rb" "test/test_types.rb" "test/test_utils_colors.rb" -v]

Tasks: TOP => default
(See full trace by running task with --trace)
ERROR: Test "ruby2.5" failed. Exiting.
dh_auto_install: dh_ruby --install /build/ruby-graphviz-1.2.2/debian/ruby-graphviz returned exit code 1
debian/rules:10: recipe for target 'binary' failed
make: *** [binary] Error 1
dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2

Full build log:
https://rbuild.fau.xxx/2018-01-23/ruby-graphviz.log

Please fix it!

Cheers,
Chris.