1 files changed, 87 insertions, 0 deletions
diff --git a/spec/graphql/mutations/merge_requests/create_spec.rb b/spec/graphql/mutations/merge_requests/create_spec.rb
new file mode 100644
index 00000000000..88acd3ed5b6
--- /dev/null
+++ b/spec/graphql/mutations/merge_requests/create_spec.rb
@@ -0,0 +1,87 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Mutations::MergeRequests::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 do
+      mutation.resolve(
+        project_path: project.full_path,
+        title: title,
+        source_branch: source_branch,
+        target_branch: target_branch,
+        description: description
+      )
+    end
+
+    let(:title) { 'MergeRequest' }
+    let(:source_branch) { 'feature' }
+    let(:target_branch) { 'master' }
+    let(:description) { nil }
+
+    let(:mutated_merge_request) { subject[:merge_request] }
+
+    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 user does not have enough permissions to create a merge request' do
+      before do
+        project.add_guest(user)
+      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
+    end
+
+    context 'when the user can create a merge request' do
+      before_all do
+        project.add_developer(user)
+      end
+
+      it 'creates a new merge request' do
+        expect { mutated_merge_request }.to change(MergeRequest, :count).by(1)
+      end
+
+      it 'returns a new merge request' do
+        expect(mutated_merge_request.title).to eq(title)
+        expect(subject[:errors]).to be_empty
+      end
+
+      context 'when optional description field is set' do
+        let(:description) { 'content' }
+
+        it 'returns a new merge request with a description' do
+          expect(mutated_merge_request.description).to eq(description)
+          expect(subject[:errors]).to be_empty
+        end
+      end
+
+      context 'when service cannot create a merge request' do
+        let(:title) { nil }
+
+        it 'does not create a new merge request' do
+          expect { mutated_merge_request }.not_to change(MergeRequest, :count)
+        end
+
+        it 'returns errors' do
+          expect(mutated_merge_request).to be_nil
+          expect(subject[:errors]).to eq(['Title can\'t be blank'])
+        end
+      end
+    end
+  end
+end