✅ test that Hyrax::Flexibility module is included

In this commit, we test that a module is included when the HYRAX_FLEXIBLE env var is set.
Issue:
- notch8/amigos#20

spec/models/hyrax/resource_spec.rb

@@ -9,6 +9,41 @@
 
   it_behaves_like 'a Hyrax::Resource'
 
+  before do
+    @hyrax_flexible_env_var = ENV['HYRAX_FLEXIBLE']
+  end
+
+  after do
+    ENV.delete('HYRAX_FLEXIBLE')
+  end
+
+  def load_resource_model
+    Hyrax.send(:remove_const, :Resource) if defined?(Hyrax::Resource)
+    load File.join('/app/samvera/hyrax-engine/app/models/hyrax/resource.rb')
+  end
+
+  context 'when HYRAX_FLEXIBLE environment variable is set' do
+    before do
+      ENV['HYRAX_FLEXIBLE'] = 'true'
+      load_resource_model
+    end
+
+    it 'includes the Hyrax::Flexibility module' do
+      expect(Hyrax::Resource.included_modules).to include(Hyrax::Flexibility)
+    end
+  end
+
+  context 'when HYRAX_FLEXIBLE environment variable is not set' do
+    before do
+      ENV.delete('HYRAX_FLEXIBLE')
+      load_resource_model
+    end
+
+    it 'does not include the Hyrax::Flexibility module' do
+      expect(Hyrax::Resource.included_modules).not_to include(Hyrax::Flexibility)
+    end
+  end
+
   describe '#events' do
     it 'includes Hyrax::WithEvents' do
       expect(resource).to respond_to(:events)