この間のアレにspec追加しました。

spec/great_class_spec.rb

@@ -0,0 +1,16 @@
+describe GreatClass do
+  describe 'some_subject_method' do
+    subject { described_class.new }
+    before do
+      allow(SomeModule).to receive(:some_important_method).and_return 'stubbed_value'
+      subject.some_subject_method
+    end
+    it 'makes itself special!' do
+      is_expected.to be_some_special_state 
+    end
+    it 'remembers to do the important thing!' do
+      expect(SomeModule).to receive(:some_important_method)
+      subject.some_subject_method
+    end
+  end
+end