Add Rubocop cop to enforce default_version in software definitions

Prevent empty build caches caused by a lack of default version.

Closes https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/8476

Signed-off-by: Balasankar 'Balu' C <balasankar@gitlab.com>

.rubocop.yml

@@ -78,6 +78,21 @@ Cop/AvoidUsingEnv:
     - lib/gitlab/util.rb
     - spec/lib/gitlab/util_spec.rb
 
+Cop/SpecifyDefaultVersion:
+  Enabled: true
+  Include:
+    - config/software/*.rb
+  Exclude:
+    # These files either use `path` source and doesn't need a default_version
+    # or is just a wrapper around other definitions
+    - config/software/gitlab-config-template.rb
+    - config/software/gitlab-cookbooks.rb
+    - config/software/gitlab-ctl-ee.rb
+    - config/software/gitlab-ctl.rb
+    - config/software/gitlab-scripts.rb
+    - config/software/gitlab-selinux.rb
+    - config/software/openssl.rb
+
 Style/MultilineIfModifier:
   Enabled: false
 

lib/rubocop/cop/specify_default_version.rb

@@ -0,0 +1,28 @@
+module Rubocop
+  module Cop
+    class SpecifyDefaultVersion < RuboCop::Cop::Base
+      NOTICE_REGEXP = '^ *default_version'.freeze
+      MSG = 'Specify default_version for the component.'.freeze
+
+      def on_new_investigation
+        return if notice_found?(processed_source)
+
+        add_global_offense(format(MSG))
+      end
+
+      private
+
+      def notice_found?(processed_source)
+        notice_regexp = Regexp.new(NOTICE_REGEXP)
+
+        notice_found = false
+        processed_source.lines.each do |line|
+          notice_found = notice_regexp.match?(line)
+          break if notice_found
+        end
+
+        notice_found
+      end
+    end
+  end
+end

lib/rubocop/rubocop.rb

@@ -1 +1,2 @@
 require_relative 'cop/avoid_using_env'
+require_relative 'cop/specify_default_version'

spec/lib/rubocop/cop/specify_default_version_spec.rb

@@ -0,0 +1,41 @@
+require 'spec_helper'
+require 'rubocop/rspec/cop_helper'
+require 'rubocop/rspec/expect_offense'
+
+require 'rubocop/cop/specify_default_version'
+
+RSpec.describe Rubocop::Cop::SpecifyDefaultVersion do
+  include CopHelper
+  include RuboCop::RSpec::ExpectOffense
+
+  subject(:cop) { described_class.new }
+
+  it 'flags violation for software definition files without default_version set' do
+    expect_offense(<<~RUBY)
+    name 'sample'
+    ^{} Specify default_version for the component.
+
+    license 'MIT'
+
+    build do
+      make
+      make install
+    end
+    RUBY
+  end
+
+  it 'does not flag violation for software definition files with default_version set' do
+    expect_no_offenses(<<~RUBY)
+    name 'sample'
+
+    license 'MIT'
+
+    default_version '1.0.0'
+
+    build do
+      make
+      make install
+    end
+    RUBY
+  end
+end