changed, changed_attributes

spec/active_record/has_aux_table_spec.rb

@@ -99,6 +99,47 @@ RSpec.describe HasAuxTable do
     expect(lot.vehicles.first.name).to eq("vehicle1")
   end
 
+  describe "#changed?" do
+    it "returns true if the main record changes" do
+      car = Car.create!(name: "Honda Civic")
+      expect(car.changed?).to be_falsey
+      car.name = "Toyota Camry"
+      expect(car.changed?).to be_truthy
+    end
+
+    it "returns true if the aux record changes" do
+      car = Car.create!(name: "Honda Civic")
+      expect(car.changed?).to be_falsey
+      car.fuel_type = "hybrid"
+      expect(car.changed?).to be_truthy
+    end
+  end
+
+  describe "#changed_attributes" do
+    # changed_attributes returns a hash with the original values of the attribute
+
+    it "returns the changed attributes of the main record" do
+      car = Car.create!(name: "Honda Civic")
+      expect(car.changed_attributes).to eq({})
+      car.name = "Toyota Camry"
+      expect(car.changed_attributes).to eq({ "name" => "Honda Civic" })
+    end
+
+    it "returns the changed attributes of the aux record when original is nil" do
+      car = Car.create!(name: "Honda Civic")
+      expect(car.changed_attributes).to eq({})
+      car.fuel_type = "hybrid"
+      expect(car.changed_attributes).to eq({ "fuel_type" => nil })
+    end
+
+    it "returns the changed attributes of the aux record when original is not nil" do
+      car = Car.create!(name: "Honda Civic", fuel_type: "gasoline")
+      expect(car.changed_attributes).to eq({})
+      car.fuel_type = "hybrid"
+      expect(car.changed_attributes).to eq({ "fuel_type" => "gasoline" })
+    end
+  end
+
   describe "database integration" do
     it "provides automatic attribute accessors for auxiliary table columns" do
       vehicle = Car.create!(name: "Honda Civic")