1 files changed, 68 insertions, 0 deletions
diff --git a/spec/graphql/mutations/merge_requests/update_spec.rb b/spec/graphql/mutations/merge_requests/update_spec.rb
new file mode 100644
index 00000000000..4a1fdf6e74b
--- /dev/null
+++ b/spec/graphql/mutations/merge_requests/update_spec.rb
@@ -0,0 +1,68 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Mutations::MergeRequests::Update do
+  let(:merge_request) { create(:merge_request) }
+  let(:user) { create(:user) }
+
+  subject(:mutation) { described_class.new(object: nil, context: { current_user: user }, field: nil) }
+
+  specify { expect(described_class).to require_graphql_authorizations(:update_merge_request) }
+
+  describe '#resolve' do
+    let(:attributes) { { title: 'new title', description: 'new description', target_branch: 'new-branch' } }
+    let(:mutated_merge_request) { subject[:merge_request] }
+
+    subject do
+      mutation.resolve(project_path: merge_request.project.full_path, iid: merge_request.iid, **attributes)
+    end
+
+    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 update the merge request' do
+      before do
+        merge_request.project.add_developer(user)
+      end
+
+      it 'applies all attributes' do
+        expect(mutated_merge_request).to eq(merge_request)
+        expect(mutated_merge_request).to have_attributes(attributes)
+        expect(subject[:errors]).to be_empty
+      end
+
+      context 'the merge request is invalid' do
+        before do
+          merge_request.allow_broken = true
+          merge_request.update!(source_project: nil)
+        end
+
+        it 'returns error information, and changes were not applied' do
+          expect(mutated_merge_request).not_to have_attributes(attributes)
+          expect(subject[:errors]).not_to be_empty
+        end
+      end
+
+      context 'our change is invalid' do
+        let(:attributes) { { target_branch: 'this is not a branch' } }
+
+        it 'returns error information, and changes were not applied' do
+          expect(mutated_merge_request).not_to have_attributes(attributes)
+          expect(subject[:errors]).not_to be_empty
+        end
+      end
+
+      context 'when passing subset of attributes' do
+        let(:attributes) { { title: 'no, this title' } }
+
+        it 'only changes the mentioned attributes' do
+          expect { subject }.not_to change { merge_request.reset.description }
+
+          expect(mutated_merge_request).to have_attributes(attributes)
+        end
+      end
+    end
+  end
+end