add empty

spec/models/logic/empty_spec.rb

@@ -0,0 +1,16 @@
+describe Logic::Constant do
+  include Logic
+
+  describe '#type' do
+    it { expect(empty.type).to eq(:empty) }
+  end
+
+  describe '#errors' do
+    it { expect(empty.errors).to eq(['empty']) }
+  end
+
+  describe '#==' do
+    it { expect(empty).to eq(empty) }
+    it { expect(empty).not_to eq(constant(true)) }
+  end
+end

spec/models/logic_spec.rb

@@ -4,5 +4,7 @@ describe Logic do
   it 'serializes deserializes' do
     expect(Logic.from_h(constant(1).to_h)).to eq(constant(1))
     expect(Logic.from_json(constant(1).to_json)).to eq(constant(1))
+
+    expect(Logic.from_h(empty.to_h)).to eq(empty)
   end
 end