1 files changed, 52 insertions, 33 deletions

diff --git a/lib/gitlab/danger/roulette.rb b/lib/gitlab/danger/roulette.rb
index ed4af3f4a43..2e6181d1cab 100644
--- a/lib/gitlab/danger/roulette.rb
+++ b/lib/gitlab/danger/roulette.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require_relative 'teammate'
+require_relative 'request_helper'
 
 module Gitlab
   module Danger
@@ -12,45 +13,49 @@ module Gitlab
         database: false
       }.freeze
 
-      Spin = Struct.new(:category, :reviewer, :maintainer, :optional_role)
+      Spin = Struct.new(:category, :reviewer, :maintainer, :optional_role, :timezone_experiment)
+
+      def team_mr_author
+        team.find { |person| person.username == mr_author_username }
+      end
 
       # Assigns GitLab team members to be reviewer and maintainer
       # for each change category that a Merge Request contains.
       #
       # @return [Array<Spin>]
-      def spin(project, categories, branch_name, timezone_experiment: false)
-        team =
-          begin
-            project_team(project)
-          rescue => err
-            warn("Reviewer roulette failed to load team data: #{err.message}")
-            []
-          end
-
-        canonical_branch_name = canonical_branch_name(branch_name)
-
-        spin_per_category = categories.each_with_object({}) do |category, memo|
+      def spin(project, categories, timezone_experiment: false)
+        spins = categories.map do |category|
           including_timezone = INCLUDE_TIMEZONE_FOR_CATEGORY.fetch(category, timezone_experiment)
 
-          memo[category] = spin_for_category(team, project, category, canonical_branch_name, timezone_experiment: including_timezone)
+          spin_for_category(project, category, timezone_experiment: including_timezone)
         end
 
-        spin_per_category.map do |category, spin|
-          case category
+        backend_spin = spins.find { |spin| spin.category == :backend }
+
+        spins.each do |spin|
+          including_timezone = INCLUDE_TIMEZONE_FOR_CATEGORY.fetch(spin.category, timezone_experiment)
+          case spin.category
+          when :qa
+            # MR includes QA changes, but also other changes, and author isn't an SET
+            if categories.size > 1 && !team_mr_author&.reviewer?(project, spin.category, [])
+              spin.optional_role = :maintainer
+            end
           when :test
+            spin.optional_role = :maintainer
+
             if spin.reviewer.nil?
               # Fetch an already picked backend reviewer, or pick one otherwise
-              spin.reviewer = spin_per_category[:backend]&.reviewer || spin_for_category(team, project, :backend, canonical_branch_name).reviewer
+              spin.reviewer = backend_spin&.reviewer || spin_for_category(project, :backend, timezone_experiment: including_timezone).reviewer
             end
           when :engineering_productivity
             if spin.maintainer.nil?
               # Fetch an already picked backend maintainer, or pick one otherwise
-              spin.maintainer = spin_per_category[:backend]&.maintainer || spin_for_category(team, project, :backend, canonical_branch_name).maintainer
+              spin.maintainer = backend_spin&.maintainer || spin_for_category(project, :backend, timezone_experiment: including_timezone).maintainer
             end
           end
-
-          spin
         end
+
+        spins
       end
 
       # Looks up the current list of GitLab team members and parses it into a
@@ -73,14 +78,9 @@ module Gitlab
       # @return [Array<Teammate>]
       def project_team(project_name)
         team.select { |member| member.in_project?(project_name) }
-      end
-
-      def canonical_branch_name(branch_name)
-        branch_name.gsub(/^[ce]e-|-[ce]e$/, '')
-      end
-
-      def new_random(seed)
-        Random.new(Digest::MD5.hexdigest(seed).to_i(16))
+      rescue => err
+        warn("Reviewer roulette failed to load team data: #{err.message}")
+        []
       end
 
       # Known issue: If someone is rejected due to OOO, and then becomes not OOO, the
@@ -113,16 +113,35 @@ module Gitlab
       # @param [Teammate] person
       # @return [Boolean]
       def mr_author?(person)
-        person.username == gitlab.mr_author
+        person.username == mr_author_username
+      end
+
+      def mr_author_username
+        helper.gitlab_helper&.mr_author || `whoami`
+      end
+
+      def mr_source_branch
+        return `git rev-parse --abbrev-ref HEAD` unless helper.gitlab_helper&.mr_json
+
+        helper.gitlab_helper.mr_json['source_branch']
+      end
+
+      def mr_labels
+        helper.gitlab_helper&.mr_labels || []
+      end
+
+      def new_random(seed)
+        Random.new(Digest::MD5.hexdigest(seed).to_i(16))
       end
 
       def spin_role_for_category(team, role, project, category)
         team.select do |member|
-          member.public_send("#{role}?", project, category, gitlab.mr_labels) # rubocop:disable GitlabSecurity/PublicSend
+          member.public_send("#{role}?", project, category, mr_labels) # rubocop:disable GitlabSecurity/PublicSend
         end
       end
 
-      def spin_for_category(team, project, category, branch_name, timezone_experiment: false)
+      def spin_for_category(project, category, timezone_experiment: false)
+        team = project_team(project)
         reviewers, traintainers, maintainers =
           %i[reviewer traintainer maintainer].map do |role|
             spin_role_for_category(team, role, project, category)
@@ -132,11 +151,11 @@ module Gitlab
         # https://gitlab.com/gitlab-org/gitlab/issues/26723
 
         # Make traintainers have triple the chance to be picked as a reviewer
-        random = new_random(branch_name)
+        random = new_random(mr_source_branch)
         reviewer = spin_for_person(reviewers + traintainers + traintainers, random: random, timezone_experiment: timezone_experiment)
         maintainer = spin_for_person(maintainers, random: random, timezone_experiment: timezone_experiment)
 
-        Spin.new(category, reviewer, maintainer)
+        Spin.new(category, reviewer, maintainer, false, timezone_experiment)
       end
     end
   end