find_by through collection proxy

spec/active_record/aux_table_spec.rb

@@ -305,6 +305,12 @@ RSpec.describe HasAuxTable do
         found_car = Car.find_by(fuel_type: "diesel")
         expect(found_car).to be_nil
       end
+
+      it "works with find_by!" do
+        expect { Car.find_by!(fuel_type: "diesel") }.to raise_error(
+          ActiveRecord::RecordNotFound
+        )
+      end
     end
 
     describe "where method with automatic joins" do
@@ -722,6 +728,18 @@ RSpec.describe HasAuxTable do
         driver = @car.drivers.create!(name: "John Doe")
         expect { driver.destroy }.to change { @car.reload.drivers.count }.by(-1)
       end
+
+      it "can be queried through the association" do
+        driver = @car.drivers.create!(name: "John Doe", license_number: 123_456)
+        expect(@car.drivers.where(name: "John Doe")).to eq([driver])
+
+        drivers = @car.drivers
+        d = drivers.find_by!(license_number: 123_456)
+        expect(d.id).to eq(driver.id)
+
+        d = drivers.find_by(license_number: 123_456)
+        expect(d.id).to eq(driver.id)
+      end
     end
 
     describe "#reload" do