Increase coverage

lib/ams/serializer.rb

@@ -128,13 +128,13 @@ module AMS
       #   #=> { data: [ { id: 1, type: :users}, { id: 2, type: :users] } }
       def relation(relation_name, type:, to:, key: relation_name, **options)
         _fields << key
-        _relations[relation_name] = { key: key, type: type, to: to }
         case to
         when :many then _relation_to_many(relation_name, type: type, key: key, **options)
         when :one then _relation_to_one(relation_name, type: type, key: key, **options)
         else
           fail ArgumentError, "UnknownRelationship to='#{to}'"
         end
+        _relations[relation_name] = { key: key, type: type, to: to }
       end
 
       # @example

test/unit/serializer/relationships_test.rb

@@ -7,7 +7,6 @@ module AMS
       class ParentModelSerializer < Serializer
         # TODO: test to: :many without :ids option
         # TODO: test to: :one without :id option
-        # TODO: test to: :unknown_option raises ArgumentError
         relation :child_models, type: :comments, to: :many, ids: "object.child_models.map(&:id)"
         relation :child_model, type: :comments, to: :one, id: "object.child_model.id"
       end
@@ -22,6 +21,27 @@ module AMS
         @serializer_instance = @serializer_class.new(@object)
       end
 
+      def test_relation_macro_missing_type
+        exception = assert_raises(ArgumentError) do
+          ParentModelSerializer.relation :missing_type, to: :anything
+        end
+        assert_match(/missing keyword: type/, exception.message)
+      end
+
+      def test_relation_macro_bad_to
+        exception = assert_raises(ArgumentError) do
+          ParentModelSerializer.relation :unknown_relation_to, type: :anything, to: :unknown_option
+        end
+        assert_match(/UnknownRelationship to='unknown_option'/, exception.message)
+      end
+
+      def test_relation_macro_missing_to
+        exception = assert_raises(ArgumentError) do
+          ParentModelSerializer.relation :missing_relation_to, type: :anything
+        end
+        assert_match(/missing keyword: to/, exception.message)
+      end
+
       def test_model_instance_relations
         expected_relations = {
           child_models: {