Extend resolver to commit to a new branch

Users may want to create a new branch along with their commit, as when
creating a new merge request.

This change adds an optional
start_branch parameter that is used to initialize a new branch.

app/graphql/mutations/commits/create.rb

@@ -13,7 +13,11 @@ module Mutations
 
       argument :branch, GraphQL::STRING_TYPE,
                required: true,
-               description: 'Name of the branch'
+               description: 'Name of the branch to commit into, it can be a new branch'
+
+      argument :start_branch, GraphQL::STRING_TYPE,
+               required: false,
+               description: 'If on a new branch, name of the original branch'
 
       argument :message,
                GraphQL::STRING_TYPE,
@@ -32,13 +36,13 @@ module Mutations
 
       authorize :push_code
 
-      def resolve(project_path:, branch:, message:, actions:)
+      def resolve(project_path:, branch:, message:, actions:, **args)
         project = authorized_find!(full_path: project_path)
 
         attributes = {
           commit_message: message,
           branch_name: branch,
-          start_branch: branch,
+          start_branch: args[:start_branch] || branch,
           actions: actions.map { |action| action.to_h }
         }
 

changelogs/unreleased/263144-commit-to-new-branch.yml

+---
+title: Extend GraphQL API to commit to a new branch in a single operation
+merge_request: 47203
+author:
+type: changed

doc/api/graphql/reference/gitlab_schema.graphql

@@ -2996,7 +2996,7 @@ input CommitCreateInput {
   actions: [CommitAction!]!
 
   """
-  Name of the branch
+  Name of the branch to commit into, it can be a new branch
   """
   branch: String!
 
@@ -3014,6 +3014,11 @@ input CommitCreateInput {
   Project full path the branch is associated with
   """
   projectPath: ID!
+
+  """
+  If on a new branch, name of the original branch
+  """
+  startBranch: String
 }
 
 """

doc/api/graphql/reference/gitlab_schema.json

@@ -8114,7 +8114,7 @@
             },
             {
               "name": "branch",
-              "description": "Name of the branch",
+              "description": "Name of the branch to commit into, it can be a new branch",
               "type": {
                 "kind": "NON_NULL",
                 "name": null,
@@ -8126,6 +8126,16 @@
               },
               "defaultValue": null
             },
+            {
+              "name": "startBranch",
+              "description": "If on a new branch, name of the original branch",
+              "type": {
+                "kind": "SCALAR",
+                "name": "String",
+                "ofType": null
+              },
+              "defaultValue": null
+            },
             {
               "name": "message",
               "description": "Raw commit message",

spec/graphql/mutations/commits/create_spec.rb

@@ -5,8 +5,9 @@ require 'spec_helper'
 RSpec.describe Mutations::Commits::Create do
   subject(:mutation) { described_class.new(object: nil, context: context, field: nil) }
 
-  let_it_be(:project) { create(:project, :public, :repository) }
   let_it_be(:user) { create(:user) }
+  let_it_be(:project) { create(:project, :public, :repository) }
+
   let(:context) do
     GraphQL::Query::Context.new(
       query: OpenStruct.new(schema: nil),
@@ -18,9 +19,10 @@ RSpec.describe Mutations::Commits::Create do
   specify { expect(described_class).to require_graphql_authorizations(:push_code) }
 
   describe '#resolve' do
-    subject { mutation.resolve(project_path: project.full_path, branch: branch, message: message, actions: actions) }
+    subject { mutation.resolve(project_path: project.full_path, branch: branch, start_branch: start_branch, message: message, actions: actions) }
 
     let(:branch) { 'master' }
+    let(:start_branch) { nil }
     let(:message) { 'Commit message' }
     let(:actions) do
       [
@@ -142,6 +144,29 @@ RSpec.describe Mutations::Commits::Create do
         end
       end
 
+      context 'when branch does not exist and a start branch is provided' do
+        let(:branch) { 'my-branch' }
+        let(:start_branch) { 'master' }
+        let(:actions) do
+          [
+            {
+              action: 'create',
+              file_path: 'ANOTHER_FILE.md',
+              content: 'Bye'
+            }
+          ]
+        end
+
+        it 'returns a new commit' do
+          expect(mutated_commit).to have_attributes(message: message, project: project)
+          expect(subject[:errors]).to be_empty
+
+          expect_to_contain_deltas([
+            a_hash_including(a_mode: '0', b_mode: '100644', new_file: true, new_path: 'ANOTHER_FILE.md')
+          ])
+        end
+      end
+
       context 'when message is not set' do
         let(:message) { nil }
 

spec/requests/api/graphql/mutations/commits/create_spec.rb

@@ -23,6 +23,18 @@ RSpec.describe 'Creation of a new commit' do
   let(:mutation) { graphql_mutation(:commit_create, input) }
   let(:mutation_response) { graphql_mutation_response(:commit_create) }
 
+  shared_examples 'a commit is successful' do
+    it 'creates a new commit' do
+      post_graphql_mutation(mutation, current_user: current_user)
+
+      expect(response).to have_gitlab_http_status(:success)
+
+      expect(mutation_response['commit']).to include(
+        'title' => message
+      )
+    end
+  end
+
   context 'the user is not allowed to create a commit' do
     it_behaves_like 'a mutation that returns a top-level access error'
   end
@@ -32,14 +44,7 @@ RSpec.describe 'Creation of a new commit' do
       project.add_developer(current_user)
     end
 
-    it 'creates a new commit' do
-      post_graphql_mutation(mutation, current_user: current_user)
-
-      expect(response).to have_gitlab_http_status(:success)
-      expect(mutation_response['commit']).to include(
-        'title' => message
-      )
-    end
+    it_behaves_like 'a commit is successful'
 
     context 'when branch is not correct' do
       let(:branch) { 'unknown' }
@@ -47,5 +52,22 @@ RSpec.describe 'Creation of a new commit' do
       it_behaves_like 'a mutation that returns errors in the response',
         errors: ['You can only create or edit files when you are on a branch']
     end
+
+    context 'when branch is new, and a start_branch is defined' do
+      let(:input) { { project_path: project.full_path, branch: branch, start_branch: start_branch, message: message, actions: actions } }
+      let(:branch) { 'new-branch' }
+      let(:start_branch) { 'master' }
+      let(:actions) do
+        [
+          {
+            action: 'CREATE',
+            filePath: 'ANOTHER_FILE.md',
+            content: 'Bye'
+          }
+        ]
+      end
+
+      it_behaves_like 'a commit is successful'
+    end
   end
 end