diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 4d6ef44..19aa5c3 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -6,52 +6,18 @@ jobs:
   build:
     strategy:
       matrix:
-        ruby_version: ['3.0', '2.7', '2.6']
-
-        gemfile:
-          - gemfiles/rails_61.gemfile
-          - gemfiles/rails_60.gemfile
-
-        include:
-          - ruby_version: ruby-head
-            gemfile: gemfiles/rails_edge.gemfile
-            allow_failures: 'true'
-          - ruby_version: '3.0'
-            gemfile: gemfiles/rails_edge.gemfile
-            allow_failures: 'true'
-
-          - ruby_version: '2.7'
-            gemfile: gemfiles/rails_edge.gemfile
-            allow_failures: 'true'
-
-          - ruby_version: '2.6'
-            gemfile: gemfiles/rails_52.gemfile
-          - ruby_version: '2.6'
-            gemfile: gemfiles/rails_51.gemfile
-          - ruby_version: '2.6'
-            gemfile: gemfiles/rails_50.gemfile
-          - ruby_version: '2.6'
-            gemfile: gemfiles/rails_42.gemfile
-            bundler_version: '1'
-
-          - ruby_version: '2.5'
-            gemfile: gemfiles/rails_52.gemfile
-          - ruby_version: '2.5'
-            gemfile: gemfiles/rails_42.gemfile
-            bundler_version: '1'
+        ruby: ['3.2', '3.3', '3.4', "4.0"]
+        rails: ["7.1", "7.2", "8.0", "8.1"]
 
     runs-on: ubuntu-latest
 
     env:
-      BUNDLE_GEMFILE: ${{ matrix.gemfile }}
+      BUNDLE_GEMFILE: gemfiles/rails_${{ matrix.rails }}.gemfile
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: ${{ matrix.ruby_version }}
-          bundler: ${{ matrix.bundler_version }}
+          ruby-version: ${{ matrix.ruby }}
           bundler-cache: true
-        continue-on-error: ${{ matrix.allow_failures == 'true' }}
       - run: bundle exec rake
-        continue-on-error: ${{ matrix.allow_failures == 'true' }}
diff --git a/.github/workflows/mend.yml b/.github/workflows/mend.yml
deleted file mode 100644
index b05ec28..0000000
--- a/.github/workflows/mend.yml
+++ /dev/null
@@ -1,29 +0,0 @@
-name: mend
-permissions:
-  contents: read
-  id-token: write
-on:
-  schedule:
-    - cron: '0 8 * * 1'
-
-jobs:
-  scan-code:
-    runs-on: ubuntu-20.04
-    steps:
-      - name: Checkout mend action
-        uses: actions/checkout@v3
-        with:
-          repository: aktsk/mend-action
-          path: ./.github/actions/mend-action
-          ssh-key: ${{ secrets.MEND_CHECKOUT_KEY }}
-      - name: Generate credential of GCP
-        uses: 'google-github-actions/auth@v1'
-        with:
-          workload_identity_provider: ${{ secrets.MEND_GCP_PROVIDER_ID }}
-          service_account: ${{ secrets.MEND_SERVICE_ACCOUNT }}
-      - name: Scan repo
-        uses: ./.github/actions/mend-action
-        with:
-          mend_api_key: ${{ secrets.MEND_API_KEY }}
-          mend_user_key: ${{ secrets.MEND_USER_KEY }}
-          slack_token: ${{ secrets.MEND_SLACK_TOKEN }}
diff --git a/.gitignore b/.gitignore
index dd48f47..ca4f590 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,5 @@ gemfiles/*.lock
 /spec/reports/
 /tmp/
 /test/dummy_app/log/*
+/test/dummy_app/tmp/*
+/vendor/bundle
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..e6c9aa3
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,35 @@
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.
+
+## [Unreleased]
+
+## [1.0.0] - 2026-01-28
+### Breaking
+- Templates are no longer executed by invoking lambdas directly; they are compiled into methods.
+
+### Changed
+- Cache template methods by code hash to reduce Ruby method cache invalidation.
+- Use a renderer subclass that includes helpers instead of extending instances.
+
+### Fixed
+- Rename the config key `cache_enabled` to `template_cache_enabled`.
+- Add `/vendor/bundle` to `.gitignore`.
+
+## [0.1.0] - 2025-09-10
+### Changed
+- Default JSON serializer switched from Oj to ActiveSupport::JSON to better align with Rails defaults.
+- Development dependencies refreshed and benchmark script fixed for the latest Ruby/Rails stacks.
+- README formatting and examples improved for clarity.
+
+### Fixed
+- Resolved `MissingTemplate` errors introduced by the Rails 8 upgrade.
+- Added coverage for rendering when template/action names differ to avoid regressions.
+
+## [0.0.0] - 2021-11-02
+### Added
+- Initial SimpleJson renderer, templates (`.simple_json.rb` lambdas), and `SimpleJson::SimpleJsonRenderable` integration.
+- Template caching toggle and configurable template paths.
+- Rails generator hooks and dummy app scaffolding for getting started.
+- Migration helpers for comparing SimpleJson output against existing Jbuilder views.
diff --git a/README.md b/README.md
index 673fb55..0c2960a 100644
--- a/README.md
+++ b/README.md
@@ -1,13 +1,17 @@
 # SimpleJson
+
 A simple & fast solution for Rails JSON rendering.
 
 ## Get started
+
 In Gemfile
+
 ```ruby
 gem 'simple_json'
 ```
 
 In controller
+
 ```ruby
 class ApplicationController < ActionController::Base
   include SimpleJson::SimpleJsonRenderable
@@ -44,10 +48,13 @@ That's all!
 Have fun!
 
 ## Special thanks
+
 This project is built on work of [jb](https://github.com/amatsuda/jb).
 
 ## Template Syntax
-SimpleJson templates are simply lambda objects that return data(Hashes or Arrays) for json.
+
+SimpleJson templates should be written in Ruby lambda format. The template code is converted into a method and then invoked to produce data (Hashes or Arrays) for JSON.
+
 ```ruby
 -> {
   {
@@ -55,7 +62,9 @@ SimpleJson templates are simply lambda objects that return data(Hashes or Arrays
   }
 }
 ```
+
 When no parameters specified, `-> {` and `}` can be omitted.
+
 ```ruby
 {
   key: @value,
@@ -83,6 +92,7 @@ Use `partial!` method to call another template in template. Note that path is al
 ```
 
 Cache helpers of simple_json is similar to jbuilder.
+
 ```ruby
 cache! key, options do
   data_to_cache
@@ -90,6 +100,7 @@ end
 ```
 
 Cache helpers uses `Rails.cache` to cache, so array keys, expirations are available. Make sure `perform_caching` is enabled.
+
 ```ruby
 cache! [key1, key2], expires_in: 10.minutes do
   data_to_cache
@@ -97,6 +108,7 @@ end
 ```
 
 `cache_if!` is also available
+
 ```ruby
 cache_if! boolean, key1, options do
   data_to_cache
@@ -104,151 +116,153 @@ end
 ```
 
 You can set key_prefix for caching like this
+
 ```ruby
 SimpleJson.cache_key_prefix = "MY_PREFIX"
 ```
 
 ## Configurations
+
 Load all templates on boot. (For production)
 Templates loaded will not load again, so it is not recommended in development environment.
+
 ```ruby
 # config/environments/production.rb
 SimpleJson.enable_template_cache
 ```
 
 The default path for templates is `app/views`, you can change it by
+
 ```ruby
 SimpleJson.template_paths.append("app/simple_jsons")
 # or
 SimpleJson.template_paths=["app/views", "app/simple_jsons"]
 ```
+
 Note that these paths should not be eager loaded cause using .rb as suffix.
 
-SimpleJson uses Oj as json serializer by default. Modules with `#encode` and `#decode` method can be used here.
+SimpleJson uses ActiveSupport::JSON as the default JSON serializer. If you want to change to a module that has `#encode` and `#decode` methods, such as the Oj gem, you can do so as follows.
+
 ```ruby
-SimpleJson.json_module = ActiveSupport::JSON
+
+# define Custom Json class
+# ex. config/initializers/simple_json/json.rb
+module SimpleJson
+  module Json
+    class Oj
+      def self.encode(json)
+        ::Oj.dump(json, mode: :rails)
+      end
+
+      def self.decode(json_string)
+        ::Oj.load(json_string, mode: :rails)
+      end
+    end
+  end
+end
+
+SimpleJson.json_module = SimpleJson::Json::Oj
 ```
 
 ## The Generator
+
 SimpleJson extends the default Rails scaffold generator and adds some simple_json templates. If you don't need them, please configure like so.
+
 ```rb
 Rails.application.config.generators.simple_json false
 ```
 
 ## Benchmarks
+
 Here're the results of a benchmark (which you can find [here](https://github.com/aktsk/simple_json/blob/master/test/dummy_app/app/controllers/benchmarks_controller.rb) in this repo) rendering a collection to JSON.
 
-### RAILS_ENV=development
 ```
 % ./bin/benchmark.sh
 
-* Rendering 10 partials via render_partial
-Warming up --------------------------------------
-                  jb   257.000  i/100ms
-            jbuilder   108.000  i/100ms
-         simple_json     2.039k i/100ms
-Calculating -------------------------------------
-                  jb      2.611k (± 7.1%) i/s -     13.107k in   5.046110s
-            jbuilder      1.084k (± 3.5%) i/s -      5.508k in   5.088845s
-         simple_json     20.725k (± 4.4%) i/s -    103.989k in   5.026914s
-
-Comparison:
-         simple_json:    20725.5 i/s
-                  jb:     2610.5 i/s - 7.94x  (± 0.00) slower
-            jbuilder:     1083.8 i/s - 19.12x  (± 0.00) slower
-
-
-* Rendering 100 partials via render_partial
-Warming up --------------------------------------
-                  jb    88.000  i/100ms
-            jbuilder    14.000  i/100ms
-         simple_json   290.000  i/100ms
-Calculating -------------------------------------
-                  jb    928.202  (± 5.0%) i/s -      4.664k in   5.037314s
-            jbuilder    137.980  (± 6.5%) i/s -    700.000  in   5.094658s
-         simple_json      2.931k (± 5.2%) i/s -     14.790k in   5.060707s
-
-Comparison:
-         simple_json:     2931.1 i/s
-                  jb:      928.2 i/s - 3.16x  (± 0.00) slower
-            jbuilder:      138.0 i/s - 21.24x  (± 0.00) slower
-
+SimpleJson Benchmark
+ruby: 4.0.1
+rails: 8.1.1
+json: 2.15.2
+oj: 3.16.11
+----------------------
 
-* Rendering 1000 partials via render_partial
+* Rendering 10 partials via render_to_string
+ruby 4.0.1 (2026-01-13 revision e04267a14b) +PRISM [arm64-darwin24]
 Warming up --------------------------------------
-                  jb    11.000  i/100ms
-            jbuilder     1.000  i/100ms
-         simple_json    29.000  i/100ms
+                  jb    23.000 i/100ms
+            jbuilder    30.000 i/100ms
+     simple_json(oj)    40.000 i/100ms
+simple_json(AS::json)
+                        46.000 i/100ms
 Calculating -------------------------------------
-                  jb    106.150  (± 5.7%) i/s -    539.000  in   5.094255s
-            jbuilder     13.012  (± 7.7%) i/s -     65.000  in   5.054016s
-         simple_json    271.683  (± 5.2%) i/s -      1.363k in   5.030646s
+                  jb    298.518 (±23.4%) i/s    (3.35 ms/i) -      1.426k in   5.019370s
+            jbuilder    255.925 (± 4.3%) i/s    (3.91 ms/i) -      1.290k in   5.052973s
+     simple_json(oj)    270.192 (± 3.7%) i/s    (3.70 ms/i) -      1.360k in   5.039635s
+simple_json(AS::json)
+                        297.476 (±10.1%) i/s    (3.36 ms/i) -      1.518k in   5.145803s
 
 Comparison:
-         simple_json:      271.7 i/s
-                  jb:      106.1 i/s - 2.56x  (± 0.00) slower
-            jbuilder:       13.0 i/s - 20.88x  (± 0.00) slower
-```
-### RAILS_ENV=production
-```
-% RAILS_ENV=production ./bin/benchmark.sh
+                  jb:      298.5 i/s
+simple_json(AS::json):      297.5 i/s - same-ish: difference falls within error
+     simple_json(oj):      270.2 i/s - same-ish: difference falls within error
+            jbuilder:      255.9 i/s - same-ish: difference falls within error
 
-* Rendering 10 partials via render_partial
-Warming up --------------------------------------
-                  jb   246.000  i/100ms
-            jbuilder    97.000  i/100ms
-         simple_json     1.957k i/100ms
-Calculating -------------------------------------
-                  jb      2.611k (± 4.1%) i/s -     13.038k in   5.002304s
-            jbuilder    972.031  (± 4.7%) i/s -      4.850k in   5.001200s
-         simple_json     20.383k (± 3.8%) i/s -    101.764k in   4.999989s
 
-Comparison:
-         simple_json:    20382.8 i/s
-                  jb:     2611.3 i/s - 7.81x  (± 0.00) slower
-            jbuilder:      972.0 i/s - 20.97x  (± 0.00) slower
-
-
-* Rendering 100 partials via render_partial
+* Rendering 100 partials via render_to_string
+ruby 4.0.1 (2026-01-13 revision e04267a14b) +PRISM [arm64-darwin24]
 Warming up --------------------------------------
-                  jb    90.000  i/100ms
-            jbuilder    11.000  i/100ms
-         simple_json   280.000  i/100ms
+                  jb    19.000 i/100ms
+            jbuilder    14.000 i/100ms
+     simple_json(oj)    15.000 i/100ms
+simple_json(AS::json)
+                        26.000 i/100ms
 Calculating -------------------------------------
-                  jb    883.446  (± 4.8%) i/s -      4.410k in   5.003438s
-            jbuilder    119.932  (± 8.3%) i/s -    605.000  in   5.085382s
-         simple_json      2.886k (± 4.2%) i/s -     14.560k in   5.054327s
+                  jb    186.051 (±12.9%) i/s    (5.37 ms/i) -    912.000 in   5.075117s
+            jbuilder    144.279 (± 2.1%) i/s    (6.93 ms/i) -    728.000 in   5.048538s
+     simple_json(oj)    159.254 (± 1.9%) i/s    (6.28 ms/i) -    810.000 in   5.088178s
+simple_json(AS::json)
+                        249.690 (± 6.0%) i/s    (4.00 ms/i) -      1.248k in   5.017042s
 
 Comparison:
-         simple_json:     2885.7 i/s
-                  jb:      883.4 i/s - 3.27x  (± 0.00) slower
-            jbuilder:      119.9 i/s - 24.06x  (± 0.00) slower
+simple_json(AS::json):      249.7 i/s
+                  jb:      186.1 i/s - 1.34x  slower
+     simple_json(oj):      159.3 i/s - 1.57x  slower
+            jbuilder:      144.3 i/s - 1.73x  slower
 
 
-* Rendering 1000 partials via render_partial
+* Rendering 1000 partials via render_to_string
+ruby 4.0.1 (2026-01-13 revision e04267a14b) +PRISM [arm64-darwin24]
 Warming up --------------------------------------
-                  jb    12.000  i/100ms
-            jbuilder     1.000  i/100ms
-         simple_json    32.000  i/100ms
+                  jb     4.000 i/100ms
+            jbuilder     2.000 i/100ms
+     simple_json(oj)     2.000 i/100ms
+simple_json(AS::json)
+                        10.000 i/100ms
 Calculating -------------------------------------
-                  jb    124.627  (± 4.8%) i/s -    624.000  in   5.018515s
-            jbuilder     12.710  (± 7.9%) i/s -     64.000  in   5.073018s
-         simple_json    314.896  (± 3.2%) i/s -      1.600k in   5.086509s
+                  jb     48.691 (± 2.1%) i/s   (20.54 ms/i) -    244.000 in   5.013815s
+            jbuilder     27.930 (± 3.6%) i/s   (35.80 ms/i) -    140.000 in   5.016897s
+     simple_json(oj)     29.083 (± 6.9%) i/s   (34.38 ms/i) -    146.000 in   5.039076s
+simple_json(AS::json)
+                         99.792 (± 7.0%) i/s   (10.02 ms/i) -    500.000 in   5.037716s
 
 Comparison:
-         simple_json:      314.9 i/s
-                  jb:      124.6 i/s - 2.53x  (± 0.00) slower
-            jbuilder:       12.7 i/s - 24.78x  (± 0.00) slower
+simple_json(AS::json):       99.8 i/s
+                  jb:       48.7 i/s - 2.05x  slower
+     simple_json(oj):       29.1 i/s - 3.43x  slower
+            jbuilder:       27.9 i/s - 3.57x  slower
 ```
 
 ## Migrating from Jbuilder
+
 When migrating from Jbuilder, you can include `Migratable` in controller for migrating mode.
+
 ```
 include SimpleJson::SimpleJsonRenderable
 include SimpleJson::Migratable
 ```
 
 In migrating mode
+
 - Comparision will be performed for simple_json and ActionView render(Jbuilder) result.
 - simple_json partials not found will use Jbuilder partial as an alternative.
 
@@ -256,7 +270,7 @@ Note that render will be performed twice, so using it in production mode is not
 
 ## Contributing
 
-Pull requests are welcome on GitHub at https://github.com/aktsk/simple_json.
+Pull requests are welcome on GitHub at <https://github.com/aktsk/simple_json>.
 
 ## License
 
diff --git a/gemfiles/rails_42.gemfile b/gemfiles/rails_42.gemfile
deleted file mode 100644
index 58018ef..0000000
--- a/gemfiles/rails_42.gemfile
+++ /dev/null
@@ -1,9 +0,0 @@
-# frozen_string_literal: true
-
-source 'https://rubygems.org'
-
-gemspec path: '../'
-
-gem 'jbuilder'
-gem 'nokogiri', RUBY_VERSION < '2.1' ? '~> 1.6.0' : '>= 1.7'
-gem 'rails', '~> 4.2.0'
diff --git a/gemfiles/rails_52.gemfile b/gemfiles/rails_52.gemfile
deleted file mode 100644
index 1b91b90..0000000
--- a/gemfiles/rails_52.gemfile
+++ /dev/null
@@ -1,8 +0,0 @@
-# frozen_string_literal: true
-
-source 'https://rubygems.org'
-
-gemspec path: '../'
-
-gem 'jbuilder'
-gem 'rails', '~> 5.2.0'
diff --git a/gemfiles/rails_61.gemfile b/gemfiles/rails_7.1.gemfile
similarity index 83%
rename from gemfiles/rails_61.gemfile
rename to gemfiles/rails_7.1.gemfile
index 51bf378..021c42f 100644
--- a/gemfiles/rails_61.gemfile
+++ b/gemfiles/rails_7.1.gemfile
@@ -5,5 +5,5 @@ source 'https://rubygems.org'
 gemspec path: '../'
 
 gem 'jbuilder'
-gem 'rails', '~> 6.1.0'
+gem 'rails', '~> 7.1.0'
 gem 'selenium-webdriver'
diff --git a/gemfiles/rails_60.gemfile b/gemfiles/rails_7.2.gemfile
similarity index 83%
rename from gemfiles/rails_60.gemfile
rename to gemfiles/rails_7.2.gemfile
index 1975ecc..d7339d9 100644
--- a/gemfiles/rails_60.gemfile
+++ b/gemfiles/rails_7.2.gemfile
@@ -5,5 +5,5 @@ source 'https://rubygems.org'
 gemspec path: '../'
 
 gem 'jbuilder'
-gem 'rails', '~> 6.0.0'
+gem 'rails', '~> 7.2.0'
 gem 'selenium-webdriver'
diff --git a/gemfiles/rails_50.gemfile b/gemfiles/rails_8.0.gemfile
similarity index 66%
rename from gemfiles/rails_50.gemfile
rename to gemfiles/rails_8.0.gemfile
index 5b3e5a7..718c4af 100644
--- a/gemfiles/rails_50.gemfile
+++ b/gemfiles/rails_8.0.gemfile
@@ -5,4 +5,5 @@ source 'https://rubygems.org'
 gemspec path: '../'
 
 gem 'jbuilder'
-gem 'rails', '~> 5.0.0'
+gem 'rails', '~> 8.0.0'
+gem 'selenium-webdriver'
diff --git a/gemfiles/rails_51.gemfile b/gemfiles/rails_8.1.gemfile
similarity index 66%
rename from gemfiles/rails_51.gemfile
rename to gemfiles/rails_8.1.gemfile
index b4ed4c5..6f2a3da 100644
--- a/gemfiles/rails_51.gemfile
+++ b/gemfiles/rails_8.1.gemfile
@@ -5,4 +5,5 @@ source 'https://rubygems.org'
 gemspec path: '../'
 
 gem 'jbuilder'
-gem 'rails', '~> 5.1.0'
+gem 'rails', '~> 8.1.0'
+gem 'selenium-webdriver'
diff --git a/lib/simple_json.rb b/lib/simple_json.rb
index f95ddbd..17f54e5 100644
--- a/lib/simple_json.rb
+++ b/lib/simple_json.rb
@@ -8,14 +8,13 @@
 
 require 'simple_json/migratable'
 require 'simple_json/simple_json_renderer_for_migration'
-require 'simple_json/json'
 
 module SimpleJson
   @config = {
-    cache_enabled: false,
+    template_cache_enabled: false,
     template_paths: ['app/views'],
     cache_key_prefix: 'simple_json/views',
-    default_json_module: Json::Oj
+    default_json_module: ActiveSupport::JSON
   }
 
   class << self
diff --git a/lib/simple_json/simple_json_renderable.rb b/lib/simple_json/simple_json_renderable.rb
index eaff277..91469b6 100644
--- a/lib/simple_json/simple_json_renderable.rb
+++ b/lib/simple_json/simple_json_renderable.rb
@@ -29,7 +29,7 @@ def render_to_body(options)
       # use super when any of [:body, :plain, :html] exist in options
       return super if self.class::RENDER_FORMATS_IN_PRIORITY.any? { |key| options.key? key }
 
-      template_name = template_name(options[:template] || action_name)
+      template_name = template_name(options[:template] || options[:action] || action_name)
       if options.key?(:json)
         process_options(options)
         @rendered_format = 'application/json; charset=utf-8'
@@ -54,9 +54,7 @@ def rendered_format
     end
 
     def simple_renderer
-      @simple_renderer ||= SimpleJsonRenderer.new(self).tap do |r|
-        r.extend(_helpers) if respond_to?(:_helpers)
-      end
+      @simple_renderer ||= self.class.simple_json_renderer_class.new(self)
     end
 
     def render_json_template(template_name, **_options)
@@ -68,6 +66,14 @@ def render_json_template(template_name, **_options)
       if SimpleJson.template_cache_enabled? && !SimpleJsonRenderer.templates_loaded?
         SimpleJsonRenderer.load_all_templates!
       end
+
+      def self.simple_json_renderer_class
+        @simple_json_renderer_class ||= begin
+          klass = Class.new(SimpleJsonRenderer)
+          klass.include(_helpers) if method_defined?(:_helpers)
+          klass
+        end
+      end
     end
 
     def template_path
diff --git a/lib/simple_json/simple_json_renderer.rb b/lib/simple_json/simple_json_renderer.rb
index ba4e1a3..6283385 100644
--- a/lib/simple_json/simple_json_renderer.rb
+++ b/lib/simple_json/simple_json_renderer.rb
@@ -20,7 +20,7 @@ def load_all_templates!
           template_files = Rails.root.glob("#{path}/**/*.simple_json.rb")
           template_files.each do |file_path|
             template_path = file_path.relative_path_from(Rails.root.join(path)).to_path.delete_suffix('.simple_json.rb')
-            @renderers[template_path] = SimpleJsonTemplate.new(file_path.to_path).renderer
+            define_template_method(template_path, file_path.to_path)
           end
         end
         @templates_loaded = true
@@ -29,7 +29,7 @@ def load_all_templates!
       def load_template(template_path)
         if SimpleJson.template_cache_enabled?
           load_all_templates! unless templates_loaded?
-          renderers[template_path]
+          render_methods[template_path]
         else
           load_template_from_file(template_path)
         end
@@ -38,18 +38,36 @@ def load_template(template_path)
       def load_template_from_file(template_path)
         SimpleJson.template_paths.each do |path|
           file_path = Rails.root.join("#{path}/#{template_path}.simple_json.rb").to_path
-          return SimpleJsonTemplate.new(file_path).renderer if File.exist?(file_path)
+
+          return define_template_method(template_path, file_path) if File.exist?(file_path)
         end
 
         nil
       end
 
-      def renderers
-        @renderers ||= {}
+      def define_template_method(template_path, file_path)
+        template = SimpleJsonTemplate.new(file_path)
+        code_hash = template.code.hash
+
+        render_methods[template_path] = render_methods_cache.fetch(code_hash) do
+          @template_num ||= 0
+          @template_num += 1
+          method_name = :"template_#{@template_num}"
+          template.define_to_class(self, method_name)
+          render_methods_cache[code_hash] = method_name
+        end
+      end
+
+      def render_methods
+        @render_methods ||= {}
+      end
+
+      def render_methods_cache
+        @render_methods_cache ||= {}
       end
 
       def clear_renderers
-        @renderers = {}
+        @render_methods = {}
         @templates_loaded = false
       end
     end
@@ -60,7 +78,7 @@ def initialize(controller)
     end
 
     def renderer(template_path)
-      renderers[template_path] || self.class.load_template(template_path).tap do |renderer|
+      renderers[template_path] || SimpleJson::SimpleJsonRenderer.load_template(template_path).tap do |renderer|
         renderers[template_path] = renderer
       end
     end
@@ -70,10 +88,11 @@ def renderers
     end
 
     def render(template_name, **params)
+      method_name = renderer(template_name)
       if !params.empty?
-        instance_exec(**params, &renderer(template_name))
+        send(method_name, **params)
       else
-        instance_exec(&renderer(template_name))
+        send(method_name)
       end
     end
 
diff --git a/lib/simple_json/simple_json_template.rb b/lib/simple_json/simple_json_template.rb
index deab7b3..a375e32 100644
--- a/lib/simple_json/simple_json_template.rb
+++ b/lib/simple_json/simple_json_template.rb
@@ -7,8 +7,11 @@ def initialize(path)
       @source = File.read(path)
     end
 
-    def renderer
-      @renderer ||= eval(code, TOPLEVEL_BINDING, @path) # rubocop:disable Security/Eval
+    def define_to_class(klass, method_name)
+      method_string = to_method_string(method_name)
+      klass.class_eval(method_string, @path)
+
+      method_name
     end
 
     def code
@@ -22,5 +25,27 @@ def lambda_stringify(source)
 
       "-> { #{source} }"
     end
+
+    def method_string_from_lambda(source, method_name)
+      pattern = %r{
+        \A(?<prefix>(?:\s*\#.*\n|\s+)*)
+        ->\s*
+        (?:\((?<params_p>.*?)\)|(?<params_n>[^\{ ]*?))
+        \s*(?:\{(?<body>.*)\}|do(?<body>.*)end)
+        (?<suffix>(?:\s*\#.*|\s+)*)\z
+      }mx
+
+      match = source.match(pattern)
+      raise :parse_error unless match
+
+      params = (match[:params_p] || match[:params_n] || "").strip
+      arg_part = params.empty? ? "" : "(#{params})"
+
+      "#{match[:prefix]}def #{method_name}#{arg_part};#{match[:body]};end#{match[:suffix]}"
+    end
+
+    def to_method_string(method_name)
+      method_string_from_lambda(code, method_name)
+    end
   end
 end
diff --git a/lib/simple_json/version.rb b/lib/simple_json/version.rb
index d1d9ec1..2809975 100644
--- a/lib/simple_json/version.rb
+++ b/lib/simple_json/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module SimpleJson
-  VERSION = '0.0.0'
+  VERSION = '1.0.0'
 end
diff --git a/simple_json.gemspec b/simple_json.gemspec
index 10fa57c..c339c35 100644
--- a/simple_json.gemspec
+++ b/simple_json.gemspec
@@ -20,15 +20,16 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ['lib']
 
-  spec.add_dependency 'oj', '~> 3.13'
+  spec.add_development_dependency 'oj'
 
   spec.add_development_dependency 'action_args'
   spec.add_development_dependency 'bundler'
-  spec.add_development_dependency 'byebug'
-  spec.add_development_dependency 'rails'
+  spec.add_development_dependency 'debug'
+  spec.add_development_dependency 'rails', '>= 7.1'
   spec.add_development_dependency 'rake'
   spec.add_development_dependency 'selenium-webdriver'
   spec.add_development_dependency 'test-unit-rails'
+  spec.add_development_dependency 'mutex_m'
 
-  spec.required_ruby_version = '>= 2.5.0'
+  spec.required_ruby_version = '>= 3.2.0'
 end
diff --git a/test/dummy_app/app/controllers/api/posts_controller.rb b/test/dummy_app/app/controllers/api/posts_controller.rb
index 3722553..a0f0a9b 100644
--- a/test/dummy_app/app/controllers/api/posts_controller.rb
+++ b/test/dummy_app/app/controllers/api/posts_controller.rb
@@ -8,6 +8,12 @@ class PostsController < ActionController::API
       def show(id)
         @post = Post.find id
       end
+
+      def renamed_show(id)
+        @post = Post.find id
+
+        render :show
+      end
     end
   end
 end
diff --git a/test/dummy_app/app/controllers/benchmarks_controller.rb b/test/dummy_app/app/controllers/benchmarks_controller.rb
index f7b0761..5646a10 100644
--- a/test/dummy_app/app/controllers/benchmarks_controller.rb
+++ b/test/dummy_app/app/controllers/benchmarks_controller.rb
@@ -1,23 +1,30 @@
 # frozen_string_literal: true
 
-require 'benchmark/ips'
-
 class BenchmarksController < ApplicationController
-  def index(n = '100')
-    @comments = 1.upto(n.to_i).map { |i| Comment.new(i, nil, "comment #{i}") }
-
-    jb = render_to_string 'index_jb'
-    jbuilder = render_to_string 'index_jbuilder'
-    simple_json = render_to_string 'index_simple_json'
-    raise 'jb != jbuilder' unless jb == jbuilder
-    raise 'simple_json != jbuilder' unless simple_json == jbuilder
-
-    result = Benchmark.ips do |x|
-      x.report('jb') { render_to_string 'index_jb' }
-      x.report('jbuilder') { render_to_string 'index_jbuilder' }
-      x.report('simple_json') { render_to_string 'index_simple_json' }
-      x.compare!
-    end
-    render plain: result.data.to_s
+  before_action :prepare_comments
+
+  def self.comments
+    @comments ||= 1.upto(1000).map { |i| Comment.new(i, nil, "comment #{i}") }
+  end
+
+  def jb
+  end
+
+  def jbuilder
+  end
+
+  def simple_json_oj
+    SimpleJson.json_module = SimpleJson::Json::Oj
+  end
+
+  def simple_json_as_json
+    SimpleJson.json_module = ActiveSupport::JSON
+  end
+
+  private
+
+  def prepare_comments
+    n = params.fetch(:n, 100).to_i
+    @comments = self.class.comments.take(n)
   end
 end
diff --git a/test/dummy_app/app/views/benchmarks/_comment_jb.json.jb b/test/dummy_app/app/views/benchmarks/_comment_jb.json.jb
index 1a0202d..db578aa 100644
--- a/test/dummy_app/app/views/benchmarks/_comment_jb.json.jb
+++ b/test/dummy_app/app/views/benchmarks/_comment_jb.json.jb
@@ -1,3 +1,55 @@
 # frozen_string_literal: true
 
-{ body: comment.body }
+length = comment.body.length
+likes = comment.id * 3
+dislikes = comment.id % 4
+rating = (likes.to_f / (dislikes.zero? ? 1 : dislikes)).round(2)
+position = comment_counter + 1
+
+{
+  id: comment.id,
+  body: comment.body,
+  metrics: {
+    length: length,
+    readability: (length / 5.0).round(2),
+    engagement: {
+      likes: likes,
+      dislikes: dislikes,
+      rating: rating
+    }
+  },
+  author: {
+    name: "user-#{comment.id}",
+    active: comment.id.odd?,
+    badges: (comment.id % 3).zero? ? %w[insightful] : [],
+    contact: {
+      email: "user#{comment.id}@example.com",
+      url: "https://example.com/users/#{comment.id}"
+    },
+    settings: {
+      theme: comment.id.even? ? 'dark' : 'light',
+      timezone: "UTC+#{(comment.id % 5) - 2}"
+    }
+  },
+  tags: ['bench', "comment-#{comment.id}", (comment.id.even? ? 'even' : nil)].compact,
+  flags: {
+    pinned: position == 1,
+    hidden: (comment.id % 5).zero?
+  },
+  metadata: {
+    position: position,
+    attachments: (comment.id % 4).zero? ? [{ filename: "attachment-#{comment.id}.txt", size: comment.id * 128 }] : [],
+    history: [
+      { version: 1, updated_by: "user-#{comment.id}", updated_at: '2024-01-01T00:00:00Z' },
+      { version: 2, updated_by: "user-#{comment.id}", updated_at: '2024-01-02T00:00:00Z' }
+    ]
+  },
+  links: {
+    self: "/comments/#{comment.id}",
+    post: "/posts/#{comment.post&.id || 1}"
+  },
+  extras: {
+    mood: %w[happy neutral excited][comment.id % 3],
+    score: comment.id * position
+  }
+}
diff --git a/test/dummy_app/app/views/benchmarks/_comment_jbuilder.json.jbuilder b/test/dummy_app/app/views/benchmarks/_comment_jbuilder.json.jbuilder
index 46c16ec..0066f21 100644
--- a/test/dummy_app/app/views/benchmarks/_comment_jbuilder.json.jbuilder
+++ b/test/dummy_app/app/views/benchmarks/_comment_jbuilder.json.jbuilder
@@ -1,3 +1,61 @@
 # frozen_string_literal: true
 
+length = comment.body.length
+likes = comment.id * 3
+dislikes = comment.id % 4
+rating = (likes.to_f / (dislikes.zero? ? 1 : dislikes)).round(2)
+position = comment_counter + 1
+
+json.id comment.id
 json.body comment.body
+
+json.metrics do
+  json.length length
+  json.readability (length / 5.0).round(2)
+  json.engagement do
+    json.likes likes
+    json.dislikes dislikes
+    json.rating rating
+  end
+end
+
+json.author do
+  json.name "user-#{comment.id}"
+  json.active comment.id.odd?
+  json.badges ((comment.id % 3).zero? ? %w[insightful] : [])
+  json.contact do
+    json.email "user#{comment.id}@example.com"
+    json.url "https://example.com/users/#{comment.id}"
+  end
+  json.settings do
+    json.theme(comment.id.even? ? 'dark' : 'light')
+    json.timezone "UTC+#{(comment.id % 5) - 2}"
+  end
+end
+
+json.tags ['bench', "comment-#{comment.id}", (comment.id.even? ? 'even' : nil)].compact
+
+json.flags do
+  json.pinned position == 1
+  json.hidden (comment.id % 5).zero?
+end
+
+json.metadata do
+  json.position position
+  attachments = (comment.id % 4).zero? ? [{ filename: "attachment-#{comment.id}.txt", size: comment.id * 128 }] : []
+  json.attachments attachments
+  json.history [
+    { version: 1, updated_by: "user-#{comment.id}", updated_at: '2024-01-01T00:00:00Z' },
+    { version: 2, updated_by: "user-#{comment.id}", updated_at: '2024-01-02T00:00:00Z' }
+  ]
+end
+
+json.links do
+  json.self "/comments/#{comment.id}"
+  json.post "/posts/#{comment.post&.id || 1}"
+end
+
+json.extras do
+  json.mood %w[happy neutral excited][comment.id % 3]
+  json.score comment.id * position
+end
diff --git a/test/dummy_app/app/views/benchmarks/_comment_simple_json.simple_json.rb b/test/dummy_app/app/views/benchmarks/_comment_simple_json.simple_json.rb
index 09565b8..0d249a7 100644
--- a/test/dummy_app/app/views/benchmarks/_comment_simple_json.simple_json.rb
+++ b/test/dummy_app/app/views/benchmarks/_comment_simple_json.simple_json.rb
@@ -1,7 +1,56 @@
 # frozen_string_literal: true
 
-->(comment:) {
+->(comment:, position:) {
+  length = comment.body.length
+  likes = comment.id * 3
+  dislikes = comment.id % 4
+  rating = (likes.to_f / (dislikes.zero? ? 1 : dislikes)).round(2)
+
   {
-    body: comment.body
+    id: comment.id,
+    body: comment.body,
+    metrics: {
+      length: length,
+      readability: (length / 5.0).round(2),
+      engagement: {
+        likes: likes,
+        dislikes: dislikes,
+        rating: rating
+      }
+    },
+    author: {
+      name: "user-#{comment.id}",
+      active: comment.id.odd?,
+      badges: (comment.id % 3).zero? ? %w[insightful] : [],
+      contact: {
+        email: "user#{comment.id}@example.com",
+        url: "https://example.com/users/#{comment.id}"
+      },
+      settings: {
+        theme: comment.id.even? ? 'dark' : 'light',
+        timezone: "UTC+#{(comment.id % 5) - 2}"
+      }
+    },
+    tags: ['bench', "comment-#{comment.id}", (comment.id.even? ? 'even' : nil)].compact,
+    flags: {
+      pinned: position == 1,
+      hidden: (comment.id % 5).zero?
+    },
+    metadata: {
+      position: position,
+      attachments: (comment.id % 4).zero? ? [{ filename: "attachment-#{comment.id}.txt", size: comment.id * 128 }] : [],
+      history: [
+        { version: 1, updated_by: "user-#{comment.id}", updated_at: '2024-01-01T00:00:00Z' },
+        { version: 2, updated_by: "user-#{comment.id}", updated_at: '2024-01-02T00:00:00Z' }
+      ]
+    },
+    links: {
+      self: "/comments/#{comment.id}",
+      post: "/posts/#{comment.post&.id || 1}"
+    },
+    extras: {
+      mood: %w[happy neutral excited][comment.id % 3],
+      score: comment.id * position
+    }
   }
 }
diff --git a/test/dummy_app/app/views/benchmarks/index_jb.json.jb b/test/dummy_app/app/views/benchmarks/index_jb.json.jb
deleted file mode 100644
index 592d814..0000000
--- a/test/dummy_app/app/views/benchmarks/index_jb.json.jb
+++ /dev/null
@@ -1,3 +0,0 @@
-# frozen_string_literal: true
-
-{ comments: render(partial: 'comment_jb', collection: @comments, as: 'comment') }
diff --git a/test/dummy_app/app/views/benchmarks/index_jbuilder.json.jbuilder b/test/dummy_app/app/views/benchmarks/index_jbuilder.json.jbuilder
deleted file mode 100644
index 1dca7dc..0000000
--- a/test/dummy_app/app/views/benchmarks/index_jbuilder.json.jbuilder
+++ /dev/null
@@ -1,5 +0,0 @@
-# frozen_string_literal: true
-
-json.comments do
-  json.partial! 'comment_jbuilder', collection: @comments, as: 'comment'
-end
diff --git a/test/dummy_app/app/views/benchmarks/index_simple_json.simple_json.rb b/test/dummy_app/app/views/benchmarks/index_simple_json.simple_json.rb
deleted file mode 100644
index e37cf1e..0000000
--- a/test/dummy_app/app/views/benchmarks/index_simple_json.simple_json.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-# frozen_string_literal: true
-
-{
-  comments: @comments.map { |comment| partial!('benchmarks/_comment_simple_json', comment: comment) }
-}
diff --git a/test/dummy_app/app/views/benchmarks/jb.json.jb b/test/dummy_app/app/views/benchmarks/jb.json.jb
new file mode 100644
index 0000000..eb71ef6
--- /dev/null
+++ b/test/dummy_app/app/views/benchmarks/jb.json.jb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+lengths = @comments.map { |comment| comment.body.length }
+avg_length = lengths.empty? ? 0.0 : (lengths.sum.to_f / lengths.size).round(2)
+
+{
+  meta: {
+    total_comments: @comments.size,
+    longest_comment_length: lengths.max || 0,
+    average_comment_length: avg_length,
+    tags: %w[bench simple json],
+    flags: {
+      has_many: @comments.size > 500,
+      empty: @comments.empty?
+    }
+  },
+  comments: render(partial: 'comment_jb', collection: @comments, as: 'comment')
+}
diff --git a/test/dummy_app/app/views/benchmarks/jbuilder.json.jbuilder b/test/dummy_app/app/views/benchmarks/jbuilder.json.jbuilder
new file mode 100644
index 0000000..8a28de6
--- /dev/null
+++ b/test/dummy_app/app/views/benchmarks/jbuilder.json.jbuilder
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+lengths = @comments.map { |comment| comment.body.length }
+avg_length = lengths.empty? ? 0.0 : (lengths.sum.to_f / lengths.size).round(2)
+
+json.meta do
+  json.total_comments @comments.size
+  json.longest_comment_length lengths.max || 0
+  json.average_comment_length avg_length
+  json.tags %w[bench simple json]
+  json.flags do
+    json.has_many @comments.size > 500
+    json.empty @comments.empty?
+  end
+end
+
+json.comments do
+  json.partial! 'comment_jbuilder', collection: @comments, as: 'comment'
+end
diff --git a/test/dummy_app/app/views/benchmarks/simple_json_as_json.simple_json.rb b/test/dummy_app/app/views/benchmarks/simple_json_as_json.simple_json.rb
new file mode 100644
index 0000000..b5dc72e
--- /dev/null
+++ b/test/dummy_app/app/views/benchmarks/simple_json_as_json.simple_json.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+lengths = @comments.map { |comment| comment.body.length }
+avg_length = lengths.empty? ? 0.0 : (lengths.sum.to_f / lengths.size).round(2)
+
+{
+  meta: {
+    total_comments: @comments.size,
+    longest_comment_length: lengths.max || 0,
+    average_comment_length: avg_length,
+    tags: %w[bench simple json],
+    flags: {
+      has_many: @comments.size > 500,
+      empty: @comments.empty?
+    }
+  },
+  comments: @comments.each_with_index.map do |comment, index|
+    partial!('benchmarks/_comment_simple_json', comment: comment, position: index + 1)
+  end
+}
diff --git a/test/dummy_app/app/views/benchmarks/simple_json_oj.simple_json.rb b/test/dummy_app/app/views/benchmarks/simple_json_oj.simple_json.rb
new file mode 100644
index 0000000..b5dc72e
--- /dev/null
+++ b/test/dummy_app/app/views/benchmarks/simple_json_oj.simple_json.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+lengths = @comments.map { |comment| comment.body.length }
+avg_length = lengths.empty? ? 0.0 : (lengths.sum.to_f / lengths.size).round(2)
+
+{
+  meta: {
+    total_comments: @comments.size,
+    longest_comment_length: lengths.max || 0,
+    average_comment_length: avg_length,
+    tags: %w[bench simple json],
+    flags: {
+      has_many: @comments.size > 500,
+      empty: @comments.empty?
+    }
+  },
+  comments: @comments.each_with_index.map do |comment, index|
+    partial!('benchmarks/_comment_simple_json', comment: comment, position: index + 1)
+  end
+}
diff --git a/test/dummy_app/bin/bench.rb b/test/dummy_app/bin/bench.rb
index f99419b..a5cd789 100644
--- a/test/dummy_app/bin/bench.rb
+++ b/test/dummy_app/bin/bench.rb
@@ -1,14 +1,80 @@
 # frozen_string_literal: true
 
 require 'action_dispatch/testing/integration'
+require 'benchmark/ips'
+require 'json'
 
-puts '* Rendering 10 partials via render_partial'
-ActionDispatch::Integration::Session.new(Rails.application).get '/benchmarks.json?n=10'
+SCENARIOS = [
+  {
+    label: 'jb',
+    path: '/benchmarks/jb.json',
+    decoder: ->(body) { JSON.parse(body) }
+  },
+  {
+    label: 'jbuilder',
+    path: '/benchmarks/jbuilder.json',
+    decoder: ->(body) { JSON.parse(body) }
+  },
+  {
+    label: 'simple_json(oj)',
+    path: '/benchmarks/simple_json_oj.json',
+    decoder: ->(body) { JSON.parse(body) }
+  },
+  {
+    label: 'simple_json(AS::json)',
+    path: '/benchmarks/simple_json_as_json.json',
+    decoder: ->(body) { JSON.parse(body) }
+  }
+].freeze
 
-puts
-puts '* Rendering 100 partials via render_partial'
-ActionDispatch::Integration::Session.new(Rails.application).get '/benchmarks.json?n=100'
+SimpleJson.enable_template_cache
 
-puts
-puts '* Rendering 1000 partials via render_partial'
-ActionDispatch::Integration::Session.new(Rails.application).get '/benchmarks.json?n=1000'
+def perform_request(path, n:)
+  session = ActionDispatch::Integration::Session.new(Rails.application)
+  session.get(path, params: { n: n })
+  raise "Unexpected status #{session.response.status} for #{path}" unless session.response.successful?
+  session.response
+end
+
+def verify_payloads(n)
+  baseline = SCENARIOS.first
+  expected_response = perform_request(baseline[:path], n: n)
+  expected_payload = baseline[:decoder].call(expected_response.body)
+
+  SCENARIOS[1..].each do |scenario|
+    response = perform_request(scenario[:path], n: n)
+    if scenario[:media_type] && response.media_type != scenario[:media_type]
+      raise "#{scenario[:label]} content type mismatch: #{response.media_type}"
+    end
+
+    actual_payload = scenario[:decoder].call(response.body)
+    raise "#{scenario[:label]} payload mismatch" unless actual_payload == expected_payload
+  end
+end
+
+def benchmark_requests(n)
+  puts
+  puts "* Rendering #{n} partials via render_to_string"
+
+  verify_payloads(n)
+
+  Benchmark.ips do |x|
+    SCENARIOS.each do |scenario|
+      x.report(scenario[:label]) do
+        perform_request(scenario[:path], n: n)
+      end
+    end
+    x.compare!
+  end
+end
+
+puts 'SimpleJson Benchmark'
+puts "ruby: #{RUBY_VERSION}"
+puts "rails: #{Rails.version}"
+puts "json: #{JSON::VERSION}"
+puts "oj: #{Oj::VERSION}"
+puts "----------------------"
+
+[10, 100, 1000].each do |n|
+  benchmark_requests(n)
+end
diff --git a/test/dummy_app/config/environments/test.rb b/test/dummy_app/config/environments/test.rb
index b1d2da7..d8da507 100644
--- a/test/dummy_app/config/environments/test.rb
+++ b/test/dummy_app/config/environments/test.rb
@@ -19,7 +19,7 @@
   config.action_controller.perform_caching = false
 
   # Raise exceptions instead of rendering exception templates.
-  config.action_dispatch.show_exceptions = false
+  config.action_dispatch.show_exceptions = :none
 
   # Disable request forgery protection in test environment.
   config.action_controller.allow_forgery_protection = false
diff --git a/lib/simple_json/json.rb b/test/dummy_app/config/initializers/simple_json/json.rb
similarity index 100%
rename from lib/simple_json/json.rb
rename to test/dummy_app/config/initializers/simple_json/json.rb
diff --git a/test/dummy_app/config/routes.rb b/test/dummy_app/config/routes.rb
index f95f929..f32cd37 100644
--- a/test/dummy_app/config/routes.rb
+++ b/test/dummy_app/config/routes.rb
@@ -15,11 +15,19 @@
   resources :posts_with_cache, only: :show
   resources :posts_with_multiple_view_paths, only: :show
 
-  resources :benchmarks, only: :index
+  resources :benchmarks, only: [] do
+    collection do
+      get :jb, defaults: { format: :json }
+      get :jbuilder, defaults: { format: :json }
+      get :simple_json_oj, defaults: { format: :json }
+      get :simple_json_as_json, defaults: { format: :json }
+    end
+  end
 
   if Rails::VERSION::MAJOR >= 5
     namespace :api do
       resources :posts, only: :show
+      get '/renamed_posts/:id', to: 'posts#renamed_show'
     end
   end
   # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
diff --git a/test/features/action_controller_api_test.rb b/test/features/action_controller_api_test.rb
index 76871f0..cb72c13 100644
--- a/test/features/action_controller_api_test.rb
+++ b/test/features/action_controller_api_test.rb
@@ -12,6 +12,14 @@ class ActionControllerAPITest < ActionDispatch::IntegrationTest
 
       assert_equal json, { 'title' => 'post 1' }
     end
+
+    test 'The renamed template correctly renders a JSON' do
+      get '/api/renamed_posts/1.json'
+
+      json = response.parsed_body
+
+      assert_equal json, { 'title' => 'post 1' }
+    end
   end
 
 end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 3fea8a6..3fdfcbd 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -8,5 +8,5 @@
 
 Bundler.require
 require 'action_args'
-require 'byebug'
+require 'debug'
 require 'test/unit/rails/test_help'
diff --git a/test/unit/simple_json_template_test.rb b/test/unit/simple_json_template_test.rb
new file mode 100644
index 0000000..6d6b837
--- /dev/null
+++ b/test/unit/simple_json_template_test.rb
@@ -0,0 +1,251 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class SimpleJsonTemplateTest < Test::Unit::TestCase
+  # -> { body } form
+  test 'converts simple lambda with braces' do
+    source = '-> { "hello" }'
+    result = call_method(source, :foo)
+
+    assert_equal 'def foo; "hello" ;end', result
+  end
+
+  # ->(params) { body } form (parenthesized parameters)
+  test 'converts lambda with parenthesized parameters' do
+    source = '->(a, b) { a + b }'
+    result = call_method(source, :add)
+
+    assert_equal 'def add(a, b); a + b ;end', result
+  end
+
+  # ->params { body } form (no parentheses, no space)
+  test 'converts lambda with parameter without parentheses' do
+    source = '->a { a * 2 }'
+    result = call_method(source, :double)
+
+    assert_equal 'def double(a); a * 2 ;end', result
+  end
+
+  # -> do body end form
+  test 'converts lambda with do-end' do
+    source = '-> do "hello" end'
+    result = call_method(source, :foo)
+
+    assert_equal 'def foo; "hello" ;end', result
+  end
+
+  # ->(params) do body end form
+  test 'converts lambda with parameters and do-end' do
+    source = '->(x) do x * 2 end'
+    result = call_method(source, :double)
+
+    assert_equal 'def double(x); x * 2 ;end', result
+  end
+
+  # Multiline body
+  test 'converts multiline lambda body' do
+    source = <<~RUBY
+      -> {
+        x = 1
+        y = 2
+        x + y
+      }
+    RUBY
+    result = call_method(source, :calc)
+
+    assert_match(/def calc;/, result)
+    assert_match(/x = 1/, result)
+    assert_match(/y = 2/, result)
+    assert_match(/x \+ y/, result)
+    assert_match(/;end/, result)
+  end
+
+  # Preserve prefix comments
+  test 'preserves prefix comments' do
+    source = <<~RUBY
+      # This is a comment
+      -> { "hello" }
+    RUBY
+    result = call_method(source, :foo)
+
+    assert_match(/\A# This is a comment\n/, result)
+    assert_match(/def foo;/, result)
+  end
+
+  # Preserve suffix comments
+  test 'preserves suffix comments' do
+    source = <<~RUBY
+      -> { "hello" }
+      # trailing comment
+    RUBY
+    result = call_method(source, :foo)
+
+    assert_match(/;end\n# trailing comment/, result)
+  end
+
+  # Empty parameter list
+  test 'converts lambda with empty parentheses' do
+    source = '->() { "hello" }'
+    result = call_method(source, :foo)
+
+    assert_equal 'def foo; "hello" ;end', result
+  end
+
+  # Space before brace with no parameters
+  test 'converts lambda with space before brace' do
+    source = '->   { "hello" }'
+    result = call_method(source, :foo)
+
+    assert_equal 'def foo; "hello" ;end', result
+  end
+
+  # Multiline do-end form
+  test 'converts multiline do-end lambda' do
+    source = <<~RUBY
+      -> do
+        result = []
+        result << 1
+        result
+      end
+    RUBY
+    result = call_method(source, :build)
+
+    assert_match(/def build;/, result)
+    assert_match(/result = \[\]/, result)
+    assert_match(/;end/, result)
+  end
+
+  # --- Parameter types ---
+
+  # Default argument
+  test 'converts lambda with default parameter' do
+    source = '->(a, b = 1) { a + b }'
+    result = call_method(source, :add)
+
+    assert_equal 'def add(a, b = 1); a + b ;end', result
+  end
+
+  # Keyword arguments
+  test 'converts lambda with keyword parameters' do
+    source = '->(a:, b: 1) { a + b }'
+    result = call_method(source, :add)
+
+    assert_equal 'def add(a:, b: 1); a + b ;end', result
+  end
+
+  # Variadic arguments
+  test 'converts lambda with splat parameter' do
+    source = '->(*args) { args }'
+    result = call_method(source, :collect)
+
+    assert_equal 'def collect(*args); args ;end', result
+  end
+
+  # Block parameter
+  test 'converts lambda with block parameter' do
+    source = '->(&block) { block.call }'
+    result = call_method(source, :execute)
+
+    assert_equal 'def execute(&block); block.call ;end', result
+  end
+
+  # Double splat
+  test 'converts lambda with double splat parameter' do
+    source = '->(**opts) { opts }'
+    result = call_method(source, :options)
+
+    assert_equal 'def options(**opts); opts ;end', result
+  end
+
+  # --- Body edge cases ---
+
+  # Nested braces
+  test 'converts lambda with nested braces in body' do
+    source = '-> { { key: value } }'
+    result = call_method(source, :hash)
+
+    assert_equal 'def hash; { key: value } ;end', result
+  end
+
+  # Empty body (braces)
+  test 'converts lambda with empty body' do
+    source = '-> { }'
+    result = call_method(source, :noop)
+
+    assert_equal 'def noop; ;end', result
+  end
+
+  # Empty body (do-end)
+  test 'converts do-end lambda with empty body' do
+    source = '-> do end'
+    result = call_method(source, :noop)
+
+    assert_equal 'def noop; ;end', result
+  end
+
+  # do-end body contains end keyword
+  test 'converts do-end lambda with nested end keyword' do
+    source = '-> do if x then y end end'
+    result = call_method(source, :conditional)
+
+    assert_equal 'def conditional; if x then y end ;end', result
+  end
+
+  # Body string contains end
+  test 'converts lambda with end string in body' do
+    source = '-> { "end of string" }'
+    result = call_method(source, :message)
+
+    assert_equal 'def message; "end of string" ;end', result
+  end
+
+  # --- Prefix edge cases ---
+
+  # Multiple prefix comments
+  test 'preserves multiple prefix comments' do
+    source = <<~RUBY
+      # comment 1
+      # comment 2
+      -> { 1 }
+    RUBY
+    result = call_method(source, :foo)
+
+    assert_match(/\A# comment 1\n# comment 2\n/, result)
+    assert_match(/def foo;/, result)
+  end
+
+  # Blank line prefix
+  test 'preserves blank line prefix' do
+    source = "\n\n-> { 1 }"
+    result = call_method(source, :foo)
+
+    assert_match(/\A\n\ndef foo;/, result)
+  end
+
+  # --- Error cases ---
+
+  # Non-lambda input
+  test 'raises error for non-lambda input' do
+    source = 'def foo; end'
+
+    assert_raise(TypeError) do
+      call_method(source, :foo)
+    end
+  end
+
+  # Proc.new input
+  test 'raises error for Proc.new input' do
+    source = 'Proc.new { 1 }'
+
+    assert_raise(TypeError) do
+      call_method(source, :foo)
+    end
+  end
+
+  private
+
+  def call_method(source, method_name)
+    SimpleJson::SimpleJsonTemplate.allocate.send(:method_string_from_lambda, source, method_name)
+  end
+end