Add configurable app-level default max_depth

Author: Nitemaeric

.rubocop.yml

@@ -1,9 +1,10 @@
-require: rubocop-rspec
+plugins:
+  - rubocop-rspec
 
 inherit_from: .rubocop_todo.yml
 
 AllCops:
-  TargetRubyVersion: 3.2.5
+  TargetRubyVersion: 3.2
   NewCops: disable
   SuggestExtensions: false
 

.rubocop_todo.yml

@@ -1,11 +1,21 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2024-06-05 00:21:36 UTC using RuboCop version 1.63.4.
+# on 2025-11-17 23:28:22 UTC using RuboCop version 1.81.7.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
+# Offense count: 2
+# Configuration parameters: CountAsOne.
+RSpec/ExampleLength:
+  Max: 14
+
+# Offense count: 2
+# Configuration parameters: AllowSubject.
+RSpec/MultipleMemoizedHelpers:
+  Max: 10
+
 # Offense count: 2
 # Configuration parameters: AllowedConstants.
 Style/Documentation:

lib/transmutation.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "transmutation/class_attributes"
+
 # A performant and expressive solution for serializing Ruby objects into JSON, with a touch of opinionated "magic" ✨.
 #
 # @example Basic usage
@@ -38,6 +40,10 @@
 #     end
 #   end
 module Transmutation
+  extend ClassAttributes
+
+  class_attribute :max_depth, default: 1
+
   class Error < StandardError; end
 end
 

lib/transmutation/serialization.rb

@@ -10,7 +10,7 @@ module Serialization
     # @param max_depth [Integer] The maximum depth of nested associations to serialize.
     #
     # @return [Transmutation::Serializer] The serialized object. This will respond to `#as_json` and `#to_json`.
-    def serialize(object, namespace: nil, serializer: nil, depth: 0, max_depth: 1)
+    def serialize(object, namespace: nil, serializer: nil, depth: 0, max_depth: Transmutation.max_depth)
       if object.respond_to?(:map) && !object.respond_to?(:to_hash)
         return object.map { |item| serialize(item, namespace:, serializer:, depth:, max_depth:) }
       end

spec/lib/transmutation/serialization_spec.rb

@@ -89,4 +89,120 @@ def last_name = "Doe"
       end
     end
   end
+
+  describe ".max_depth" do
+    let(:top_level_serializer) do
+      Class.new(Transmutation::Serializer) do
+        attribute :id
+
+        has_one :first_level
+      end
+    end
+
+    let(:first_level_serializer) do
+      Class.new(Transmutation::Serializer) do
+        attribute :id
+
+        has_one :second_level
+      end
+    end
+
+    let(:second_level_serializer) do
+      Class.new(Transmutation::Serializer) do
+        attribute :id
+      end
+    end
+
+    let(:top_level_class) do
+      Class.new do
+        attr_accessor :id, :first_level
+
+        def initialize(id:, first_level:)
+          @id = id
+          @first_level = first_level
+        end
+      end
+    end
+
+    let(:first_level_class) do
+      Class.new do
+        attr_accessor :id, :second_level
+
+        def initialize(id:, second_level:)
+          @id = id
+          @second_level = second_level
+        end
+      end
+    end
+
+    let(:second_level_class) do
+      Class.new do
+        attr_accessor :id
+
+        def initialize(id:)
+          @id = id
+        end
+      end
+    end
+
+    before do
+      stub_const("TopLevelSerializer", top_level_serializer)
+      stub_const("FirstLevelSerializer", first_level_serializer)
+      stub_const("SecondLevelSerializer", second_level_serializer)
+      stub_const("TopLevel", top_level_class)
+      stub_const("FirstLevel", first_level_class)
+      stub_const("SecondLevel", second_level_class)
+    end
+
+    it "returns a default value of 1" do
+      expect(Transmutation.max_depth).to eq(1)
+    end
+
+    it "serializes only 1 level of associations" do
+      second_level = SecondLevel.new(id: 3)
+      first_level  = FirstLevel.new(id: 2, second_level:)
+      top_level    = TopLevel.new(id: 1, first_level:)
+
+      serialized = caller.serialize(top_level)
+
+      expected_json = {
+        "id" => 1,
+        "first_level" => {
+          "id" => 2
+        }
+      }
+
+      expect(serialized.as_json).to eq(expected_json)
+    end
+
+    context "when the value is set to another value" do
+      before do
+        Transmutation.max_depth = 2
+      end
+
+      it "returns the maximum depth of the serializer" do
+        expect(Transmutation.max_depth).to eq(2)
+      end
+
+      it "serializes 2 levels of associations" do
+        second_level = SecondLevel.new(id: 3)
+        first_level  = FirstLevel.new(id: 2, second_level:)
+        top_level    = TopLevel.new(id: 1, first_level:)
+
+        serialized = caller.serialize(top_level)
+
+        expected_json = {
+          "id" => 1,
+          "first_level" => {
+            "id" => 2,
+            "second_level" => {
+              "id" => 3
+            }
+          }
+        }
+
+        expect(serialized.as_json).to eq(expected_json)
+      end
+    end
+  end
 end