1 files changed, 55 insertions, 0 deletions
diff --git a/spec/graphql/mutations/branches/create_spec.rb b/spec/graphql/mutations/branches/create_spec.rb
new file mode 100644
index 00000000000..744f8f1f2bc
--- /dev/null
+++ b/spec/graphql/mutations/branches/create_spec.rb
@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Mutations::Branches::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(:context) do
+    GraphQL::Query::Context.new(
+      query: OpenStruct.new(schema: nil),
+      values: { current_user: user },
+      object: nil
+    )
+  end
+
+  describe '#resolve' do
+    subject { mutation.resolve(project_path: project.full_path, name: branch, ref: ref) }
+
+    let(:branch) { 'new_branch' }
+    let(:ref) { 'master' }
+    let(:mutated_branch) { subject[:branch] }
+
+    it 'raises an error if the resource is not accessible to the user' do
+      expect { subject }.to raise_error(Gitlab::Graphql::Errors::ResourceNotAvailable)
+    end
+
+    context 'when the user can create a branch' do
+      before do
+        project.add_developer(user)
+
+        allow_next_instance_of(::Branches::CreateService, project, user) do |create_service|
+          allow(create_service).to receive(:execute).with(branch, ref) { service_result }
+        end
+      end
+
+      context 'when service successfully creates a new branch' do
+        let(:service_result) { { status: :success, branch: double(name: branch) } }
+
+        it 'returns a new branch' do
+          expect(mutated_branch.name).to eq(branch)
+          expect(subject[:errors]).to be_empty
+        end
+      end
+
+      context 'when service fails to create a new branch' do
+        let(:service_result) { { status: :error, message: 'Branch already exists' } }
+
+        it { expect(mutated_branch).to be_nil }
+        it { expect(subject[:errors]).to eq(['Branch already exists']) }
+      end
+    end
+  end
+end