1 files changed, 23 insertions, 10 deletions
diff --git a/app/services/merge_requests/squash_service.rb b/app/services/merge_requests/squash_service.rb
index a439a380255..9d1a5d5e6d4 100644
--- a/app/services/merge_requests/squash_service.rb
+++ b/app/services/merge_requests/squash_service.rb
@@ -2,15 +2,10 @@
 
 module MergeRequests
   class SquashService < MergeRequests::WorkingCopyBaseService
-    def execute(merge_request)
-      @merge_request = merge_request
-      @repository = target_project.repository
-
-      squash || error('Failed to squash. Should be done manually.')
-    end
-
-    def squash
-      if merge_request.commits_count < 2
+    def execute
+      # If performing a squash would result in no change, then
+      # immediately return a success message without performing a squash
+      if merge_request.commits_count < 2 && message.nil?
         return success(squash_sha: merge_request.diff_head_sha)
       end
 
@@ -18,7 +13,13 @@ module MergeRequests
         return error('Squash task canceled: another squash is already in progress.')
       end
 
-      squash_sha = repository.squash(current_user, merge_request)
+      squash! || error('Failed to squash. Should be done manually.')
+    end
+
+    private
+
+    def squash!
+      squash_sha = repository.squash(current_user, merge_request, message || merge_request.default_squash_commit_message)
 
       success(squash_sha: squash_sha)
     rescue => e
@@ -26,5 +27,17 @@ module MergeRequests
       log_error(e.message)
       false
     end
+
+    def repository
+      target_project.repository
+    end
+
+    def merge_request
+      params[:merge_request]
+    end
+
+    def message
+      params[:squash_commit_message].presence
+    end
   end
 end