Merge branch '22203-reduce-duplication-in-commits-cherry_pick_service' into 'master'

Reduce duplication in `Commits::{CherryPickService,RevertService}`

## What does this MR do?

This factorize similar code from `Commits::{CherryPickService,RevertService}`.

## Why was this MR needed?

To get rid of flay offense.

## What are the relevant issue numbers?

Closes #22203

See merge request !6366

app/services/commits/change_service.rb

@@ -16,11 +16,29 @@ module Commits
       error(ex.message)
     end
 
+    private
+
     def commit
       raise NotImplementedError
     end
 
-    private
+    def commit_change(action)
+      raise NotImplementedError unless repository.respond_to?(action)
+
+      into = @create_merge_request ? @commit.public_send("#{action}_branch_name") : @target_branch
+      tree_id = repository.public_send("check_#{action}_content", @commit, @target_branch)
+
+      if tree_id
+        create_target_branch(into) if @create_merge_request
+
+        repository.public_send(action, current_user, @commit, into, tree_id)
+        success
+      else
+        error_msg = "Sorry, we cannot #{action.to_s.dasherize} this #{@commit.change_type_title} automatically.
+                     It may have already been #{action.to_s.dasherize}, or a more recent commit may have updated some of its content."
+        raise ChangeError, error_msg
+      end
+    end
 
     def check_push_permissions
       allowed = ::Gitlab::UserAccess.new(current_user, project: project).can_push_to_branch?(@target_branch)

app/services/commits/cherry_pick_service.rb

@@ -1,19 +1,7 @@
 module Commits
   class CherryPickService < ChangeService
     def commit
-      cherry_pick_into = @create_merge_request ? @commit.cherry_pick_branch_name : @target_branch
-      cherry_pick_tree_id = repository.check_cherry_pick_content(@commit, @target_branch)
-
-      if cherry_pick_tree_id
-        create_target_branch(cherry_pick_into) if @create_merge_request
-
-        repository.cherry_pick(current_user, @commit, cherry_pick_into, cherry_pick_tree_id)
-        success
-      else
-        error_msg = "Sorry, we cannot cherry-pick this #{@commit.change_type_title} automatically.
-                     It may have already been cherry-picked, or a more recent commit may have updated some of its content."
-        raise ChangeError, error_msg
-      end
+      commit_change(:cherry_pick)
     end
   end
 end

app/services/commits/revert_service.rb

@@ -1,19 +1,7 @@
 module Commits
   class RevertService < ChangeService
     def commit
-      revert_into = @create_merge_request ? @commit.revert_branch_name : @target_branch
-      revert_tree_id = repository.check_revert_content(@commit, @target_branch)
-
-      if revert_tree_id
-        create_target_branch(revert_into) if @create_merge_request
-
-        repository.revert(current_user, @commit, revert_into, revert_tree_id)
-        success
-      else
-        error_msg = "Sorry, we cannot revert this #{@commit.change_type_title} automatically.
-                     It may have already been reverted, or a more recent commit may have updated some of its content."
-        raise ChangeError, error_msg
-      end
+      commit_change(:revert)
     end
   end
 end