Add specs for graphql controller

spec/controllers/api/graphql_controller_spec.rb

@@ -0,0 +1,86 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe API::GraphqlController, type: :controller do
+  describe 'POST #execute' do
+    subject { post :execute }
+
+    it 'calls GraphQL schema#execute' do
+      expect(PokemonTradeSchema).to receive(:execute)
+      subject
+      expect(response).to have_http_status(:ok)
+    end
+
+    context 'failure occured' do
+      it 'raises error' do
+        expect(PokemonTradeSchema).to receive(:execute).and_raise('foo')
+        subject
+        expect(response).to have_http_status(:internal_server_error)
+      end
+    end
+
+    context '#ensure_hash' do
+      subject { post :execute, params: params }
+
+      context 'successfully parses' do
+        let(:params) { {variables: '{"foo": "bar"}'} }
+
+        it 'parses the parameters' do
+          subject
+          expect(response).to have_http_status(:ok)
+        end
+
+        context 'nil param' do
+          let(:params) { {variables: 'null'} }
+
+          it 'parses the parameters' do
+            subject
+            expect(response).to have_http_status(:ok)
+          end
+        end
+
+        context 'empty param' do
+          let(:params) { {variables: ''} }
+
+          it 'parses the parameters' do
+            subject
+            expect(response).to have_http_status(:ok)
+          end
+        end
+      end
+
+      context 'fails to parse' do
+        let(:params) { {variables: 'foo'} }
+        it 'parses the parameters' do
+          subject
+          expect(response).to have_http_status(:internal_server_error)
+        end
+      end
+
+      context 'unexpected param' do
+        let(:params) { {variables: 1} }
+        it 'parses the parameters' do
+          subject
+          expect(response).to have_http_status(:internal_server_error)
+        end
+      end
+    end
+
+    context 'development errors' do
+      subject { post :execute }
+
+      before do
+        allow(PokemonTradeSchema).to receive(:execute).and_raise('foo')
+        allow(Rails.env).to receive(:development?).and_return(true)
+      end
+
+      it 'renders error JSON' do
+        subject
+        json = JSON.parse(response.body)
+        expect(json).to have_key('errors')
+        expect(response).to have_http_status(:internal_server_error)
+      end
+    end
+  end
+end