Ruby 2.8.0 removes rexml gem then Gemfile or gemspec needs to add rexml gem explicitly

[yahonda]

Ruby 2.8.0 removes rexml gem then Gemfile or gemspec needs to add rexml gem explicitly.

Environment details

• OS: macOS 10.15.5 Beta (19F53f)
• Ruby version: ruby 2.8.0dev (2020-04-01T10:29:39Z master fad0a1451b) [x86_64-darwin19]
• Gem name and version: google-api-client master branch

Steps to reproduce

1. rbenv install 2.8.0-dev ; rbenv global 2.8.0 (or whatever install Ruby 2.8.0-dev)
2. git clone https://github.com/googleapis/google-api-ruby-client.git
3. cd google-api-ruby-client
4. bundle install
5. bundle exec rake

Expected behavior

It should pass.

Actual result

It gets this error. Entire output is https://gist.github.com/yahonda/f4eb287756e9656b0580def1c3d8291f

LoadError:
  cannot load such file -- rexml/parsers/streamparser
# ./spec/spec_helper.rb:42:in `require'
# ./spec/spec_helper.rb:42:in `<top (required)>'
# ./spec/google/api_client/auth/installed_app_spec.rb:1:in `require'
# ./spec/google/api_client/auth/installed_app_spec.rb:1:in `<top (required)>'

Code example

I have confirmed this change addresses this error.

% git diff master                                                                                                                                                                                         ruby280
diff --git a/google-api-client.gemspec b/google-api-client.gemspec
index 699e5f25..62cb80f5 100644
--- a/google-api-client.gemspec
+++ b/google-api-client.gemspec
@@ -30,6 +30,7 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency 'signet', '~> 0.12'
   spec.add_runtime_dependency 'googleauth', '~> 0.9'
   spec.add_runtime_dependency 'httpclient', '>= 2.8.1', '< 3.0'
+  spec.add_runtime_dependency 'rexml'
   spec.add_development_dependency 'thor', '~> 0.19'
   spec.add_development_dependency 'activesupport', '>= 4.2', '< 5.1'
 end

Additional information

• Remove rexml and rss
  Remove rexml and rss ruby/ruby#2832

• Feature feat: Automated regeneration of androidmanagement v1 client #16485
  https://bugs.ruby-lang.org/issues/16485

Cons: The users need to add rexml to their Gemfile after Ruby 2.8(3.0)

[dazuma]

Will adding the rexml gem to dependencies cause issues for earlier versions of Ruby? (i.e. does the gem work back to Ruby 2.4.x or will it conflict with the standard library copy of rexml?)

[yahonda]

I think it is safe to add rexml gem to dependencies because rexml CI has been running against Ruby 2.4 and higher.

https://github.com/ruby/rexml/blob/be62163ba12a6657679a34e472b1d29d75e0e881/.travis.yml#L6-L13

[yahonda]

I have opened ruby/rexml#28 and confirmed my assumption is correct.

ruby/rexml#28 (comment)

[yahonda]

Opened #899