Support fast unit tests in EE

Problem to solve

We have fast unit tests available when dealing with POROs but this currently only works for CE classes.

Intended users

GitLab developers

Further details

Trying to run a "fast spec" for an EE class by requiring fast_spec_helper instead of spec_helper will raise error:

Failure/Error: StubConfiguration.prepend(EE::StubConfiguration)

NameError:
  uninitialized constant EE::StubConfiguration
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/active_support.rb:60:in `block in load_missing_constant'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/active_support.rb:16:in `allow_bootsnap_retry'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/active_support.rb:59:in `load_missing_constant'
# ./spec/support/helpers/stub_configuration.rb:124:in `<main>'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `block in require_with_bootsnap_lfi'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:83:in `register'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:20:in `require_with_bootsnap_lfi'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:29:in `require'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:44:in `require_relative'
# ./spec/support/rspec.rb:1:in `<main>'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `block in require_with_bootsnap_lfi'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:83:in `register'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:20:in `require_with_bootsnap_lfi'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:29:in `require'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:44:in `require_relative'
# ./spec/fast_spec_helper.rb:7:in `<main>'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `block in require_with_bootsnap_lfi'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:83:in `register'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:20:in `require_with_bootsnap_lfi'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:29:in `require'
# ./ee/spec/lib/gitlab/ci/reports/security/locations/sast_spec.rb:3:in `<main>'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:50:in `load'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:50:in `load'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:50:in `load'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:50:in `load'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/spring-commands-rspec-1.0.4/lib/spring/commands/rspec.rb:18:in `call'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/nakayoshi_fork-0.0.4/lib/nakayoshi_fork.rb:23:in `fork'
# /Users/ogonzalez/.rvm/gems/ruby-2.5.3/gems/nakayoshi_fork-0.0.4/lib/nakayoshi_fork.rb:23:in `fork'
# -e:1:in `<main>'

Proposal

TODO

Documentation

We might need to improve https://docs.gitlab.com/ee/development/testing_guide/best_practices.html#fast-unit-tests if there is a specific setup for EE.

What does success look like, and how can we measure that?

One can use fast unit tests for EE classes.

Links / references