Add specs for Subject::Method::Instance#public?

spec/unit/mutant/subject/method/instance_spec.rb

@@ -85,6 +85,34 @@ RSpec.describe Mutant::Subject::Method::Instance do
 
     it { should eql("def foo\nend") }
   end
+
+  describe '#public?' do
+    subject { object.public? }
+
+    context 'when method is public' do
+      it { should be(true) }
+    end
+
+    context 'when method is private' do
+      before do
+        scope.class_eval do
+          private :foo
+        end
+      end
+
+      it { should be(false) }
+    end
+
+    context 'when method is protected' do
+      before do
+        scope.class_eval do
+          protected :foo
+        end
+      end
+
+      it { should be(false) }
+    end
+  end
 end
 
 RSpec.describe Mutant::Subject::Method::Instance::Memoized do