Model validations

test/models/weight_test.rb

@@ -4,4 +4,10 @@ class WeightTest < ActiveSupport::TestCase
   test "the truth" do
      assert true
    end
+   
+   test "Weight validations" do
+      weight = Weight.new
+      assert_not weight.valid?
+      assert_equal [:max], weight.errors.keys
+    end
 end