1 files changed, 55 insertions, 27 deletions

diff --git a/app/services/merge_requests/build_service.rb b/app/services/merge_requests/build_service.rb
index f3b99e1ec8c..c2fb01466df 100644
--- a/app/services/merge_requests/build_service.rb
+++ b/app/services/merge_requests/build_service.rb
@@ -1,6 +1,8 @@
 module MergeRequests
   class BuildService < MergeRequests::BaseService
     def execute
+      @issue_iid = params.delete(:issue_iid)
+
       self.merge_request = MergeRequest.new(params)
       merge_request.compare_commits = []
       merge_request.source_project  = find_source_project
@@ -18,7 +20,17 @@ module MergeRequests
 
     attr_accessor :merge_request
 
-    delegate :target_branch, :source_branch, :source_project, :target_project, :compare_commits, :wip_title, :description, :errors, to: :merge_request
+    delegate :target_branch,
+             :target_branch_ref,
+             :target_project,
+             :source_branch,
+             :source_branch_ref,
+             :source_project,
+             :compare_commits,
+             :wip_title,
+             :description,
+             :errors,
+             to: :merge_request
 
     def find_source_project
       return source_project if source_project.present? && can?(current_user, :read_project, source_project)
@@ -54,10 +66,10 @@ module MergeRequests
     def compare_branches
       compare = CompareService.new(
         source_project,
-        source_branch
+        source_branch_ref
       ).execute(
         target_project,
-        target_branch
+        target_branch_ref
       )
 
       if compare
@@ -106,37 +118,53 @@ module MergeRequests
     #   more than one commit in the MR
     #
     def assign_title_and_description
-      if match = source_branch.match(/\A(\d+)-/)
-        iid = match[1]
-      end
+      assign_title_and_description_from_single_commit
+      assign_title_from_issue
 
-      commits = compare_commits
-      if commits && commits.count == 1
-        commit = commits.first
-        merge_request.title = commit.title
-        merge_request.description ||= commit.description.try(:strip)
-      elsif iid && issue = target_project.get_issue(iid, current_user)
-        case issue
-        when Issue
-          merge_request.title = "Resolve \"#{issue.title}\""
-        when ExternalIssue
-          merge_request.title = "Resolve #{issue.title}"
-        end
+      merge_request.title ||= source_branch.titleize.humanize
+      merge_request.title = wip_title if compare_commits.empty?
+
+      append_closes_description
+    end
+
+    def append_closes_description
+      return unless issue_iid
+
+      closes_issue = "Closes ##{issue_iid}"
+
+      if description.present?
+        merge_request.description += closes_issue.prepend("\n\n")
       else
-        merge_request.title = source_branch.titleize.humanize
+        merge_request.description = closes_issue
       end
+    end
 
-      if iid
-        closes_issue = "Closes ##{iid}"
+    def assign_title_and_description_from_single_commit
+      commits = compare_commits
+
+      return unless commits&.count == 1
+
+      commit = commits.first
+      merge_request.title ||= commit.title
+      merge_request.description ||= commit.description.try(:strip)
+    end
+
+    def assign_title_from_issue
+      return unless issue
 
-        if description.present?
-          merge_request.description += closes_issue.prepend("\n\n")
-        else
-          merge_request.description = closes_issue
+      merge_request.title =
+        case issue
+        when Issue         then "Resolve \"#{issue.title}\""
+        when ExternalIssue then "Resolve #{issue.title}"
         end
-      end
+    end
+
+    def issue_iid
+      @issue_iid ||= source_branch.match(/\A(\d+)-/).try(:[], 1)
+    end
 
-      merge_request.title = wip_title if commits.empty?
+    def issue
+      @issue ||= target_project.get_issue(issue_iid, current_user)
     end
   end
 end