From def144807684e69871cba63c29c41a8fd7aa1a2e Mon Sep 17 00:00:00 2001
From: Joel Hawksley <joel@hawksley.org>
Date: Wed, 25 Sep 2024 15:48:23 -0600
Subject: [PATCH] Add basic internal testing for memory allocations (#2097)

* Add basic internal testing for memory allocations

* add RUBY_VERSION to debug output

* fix allocation counts

* fix allocation counts

* use compile cache helper

* try using cache clearing

* try using more specific ruby version targets and ensure compilation

* add allocation counts for CI ruby versions

* use counts from CI

* move require to top of file

* try removing component from compile cache to stabilize allocations

* another stabilization attempt
---
 Gemfile.lock                        |  2 ++
 docs/CHANGELOG.md                   |  4 +++
 test/sandbox/test/rendering_test.rb | 53 ++++++++++++++++-------------
 test/test_helper.rb                 |  9 +++++
 view_component.gemspec              |  1 +
 5 files changed, 46 insertions(+), 23 deletions(-)

diff --git a/Gemfile.lock b/Gemfile.lock
index 17de0de18..8538fa741 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -76,6 +76,7 @@ GEM
       tzinfo (~> 2.0)
     addressable (2.8.7)
       public_suffix (>= 2.0.2, < 7.0)
+    allocation_stats (0.1.5)
     ansi (1.5.0)
     appraisal (2.5.0)
       bundler
@@ -330,6 +331,7 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
+  allocation_stats (~> 0.1.5)
   appraisal (~> 2.4)
   benchmark-ips (~> 2.13.0)
   better_html
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index b3c577e5d..9d44e5454 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -10,6 +10,10 @@ nav_order: 5
 
 ## main
 
+* Add basic internal testing for memory allocations.
+
+    *Joel Hawksley*
+
 * Add support for request formats.
 
     *Joel Hawksley*
diff --git a/test/sandbox/test/rendering_test.rb b/test/sandbox/test/rendering_test.rb
index 6f8e66b51..afd4e1ca7 100644
--- a/test/sandbox/test/rendering_test.rb
+++ b/test/sandbox/test/rendering_test.rb
@@ -9,6 +9,19 @@ def test_render_inline
     assert_selector("div", text: "hello,world!")
   end
 
+  def test_render_inline_allocations
+    # Stabilize compilation status ahead of testing allocations to simulate rendering
+    # performance with compiled component
+    ViewComponent::CompileCache.cache.delete(MyComponent)
+    MyComponent.ensure_compiled
+
+    assert_allocations("3.4.0" => 107, "3.3.5" => 116, "3.3.0" => 129, "3.2.5" => 115, "3.1.6" => 115, "3.0.7" => 125) do
+      render_inline(MyComponent.new)
+    end
+
+    assert_selector("div", text: "hello,world!")
+  end
+
   def test_render_in_view_context
     render_in_view_context { render(MyComponent.new) }
 
@@ -717,34 +730,28 @@ def test_collection_component_present_custom_parameter_name_with_activemodel
   end
 
   def test_component_with_invalid_parameter_names
-    old_cache = ViewComponent::CompileCache.cache
-    ViewComponent::CompileCache.cache = Set.new
-
-    exception =
-      assert_raises ViewComponent::ReservedParameterError do
-        InvalidParametersComponent.compile(raise_errors: true)
-      end
+    with_new_cache do
+      exception =
+        assert_raises ViewComponent::ReservedParameterError do
+          InvalidParametersComponent.compile(raise_errors: true)
+        end
 
-    assert_match(/InvalidParametersComponent initializer can't accept the parameter/, exception.message)
-  ensure
-    ViewComponent::CompileCache.cache = old_cache
+      assert_match(/InvalidParametersComponent initializer can't accept the parameter/, exception.message)
+    end
   end
 
   def test_component_with_invalid_named_parameter_names
-    old_cache = ViewComponent::CompileCache.cache
-    ViewComponent::CompileCache.cache = Set.new
-
-    exception =
-      assert_raises ViewComponent::ReservedParameterError do
-        InvalidNamedParametersComponent.compile(raise_errors: true)
-      end
+    with_new_cache do
+      exception =
+        assert_raises ViewComponent::ReservedParameterError do
+          InvalidNamedParametersComponent.compile(raise_errors: true)
+        end
 
-    assert_match(
-      /InvalidNamedParametersComponent initializer can't accept the parameter `content`/,
-      exception.message
-    )
-  ensure
-    ViewComponent::CompileCache.cache = old_cache
+      assert_match(
+        /InvalidNamedParametersComponent initializer can't accept the parameter `content`/,
+        exception.message
+      )
+    end
   end
 
   def test_collection_component_with_trailing_comma_attr_reader
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 1e6d449bb..61e9ff33e 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 
+require "allocation_stats"
 require "simplecov"
 require "simplecov-console"
 require "rails/version"
@@ -187,3 +188,11 @@ def capture_warnings(&block)
     end
   end
 end
+
+def assert_allocations(count_map, &block)
+  trace = AllocationStats.trace(&block)
+  total = trace.allocations.all.size
+  count = count_map[RUBY_VERSION]
+
+  assert_equal count, total, "Expected #{count} allocations, got #{total} allocations for Ruby #{RUBY_VERSION}"
+end
diff --git a/view_component.gemspec b/view_component.gemspec
index 3a6f3dacb..03fc32c77 100644
--- a/view_component.gemspec
+++ b/view_component.gemspec
@@ -32,6 +32,7 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency "activesupport", [">= 5.2.0", "< 8.0"]
   spec.add_runtime_dependency "method_source", "~> 1.0"
   spec.add_runtime_dependency "concurrent-ruby", "~> 1.0"
+  spec.add_development_dependency "allocation_stats", "~> 0.1.5"
   spec.add_development_dependency "appraisal", "~> 2.4"
   spec.add_development_dependency "benchmark-ips", "~> 2.13.0"
   spec.add_development_dependency "better_html"