From 6bded942c4fa21eb15b4e5663f0980a8f947786a Mon Sep 17 00:00:00 2001
From: Robin Miller <robin@tenjin.ca>
Date: Sat, 13 Sep 2025 16:11:20 -0600
Subject: [PATCH 1/2] Add branch test coverage when available. Force track all
 files to prevent implicit file discovery missing files.

---
 test/json/test_helper.rb | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/test/json/test_helper.rb b/test/json/test_helper.rb
index a788804d..24d98170 100644
--- a/test/json/test_helper.rb
+++ b/test/json/test_helper.rb
@@ -1,14 +1,29 @@
 $LOAD_PATH.unshift(File.expand_path('../../../ext', __FILE__), File.expand_path('../../../lib', __FILE__))
 
 require 'coverage'
-Coverage.start
+
+branches_supported = Coverage.respond_to?(:supported?) && Coverage.supported?(:branches)
+
+# Coverage module must be started before SimpleCov to work around the cyclic require order.
+# Track both branches and lines, or else SimpleCov misleadingly reports 0/0 = 100% for non-branching files.
+Coverage.start(lines:    true,
+               branches: branches_supported)
 
 begin
   require 'simplecov'
 rescue LoadError
   # Don't fail Ruby's test suite
 else
-  SimpleCov.start
+  SimpleCov.start do
+    # Enabling both coverage types to let SimpleCov know to output them together in reports
+    enable_coverage :line
+    enable_coverage :branch if branches_supported
+
+    # Can't always trust SimpleCov to find files implicitly
+    track_files 'lib/**/*.rb'
+
+    add_filter 'lib/json/truffle_ruby' unless RUBY_ENGINE == 'truffleruby'
+  end
 end
 
 require 'json'

From 08b9eb0ee66abff31000fffae19ab74c907c4576 Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Thu, 18 Sep 2025 11:20:21 +0200
Subject: [PATCH 2/2] Only enable test coverage when running the test suite
 standalone

---
 Rakefile                 |  8 ++++++++
 test/json/test_helper.rb | 18 ++++++++----------
 2 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/Rakefile b/Rakefile
index c43acbc6..c1768853 100644
--- a/Rakefile
+++ b/Rakefile
@@ -6,6 +6,14 @@ include RbConfig
 require 'rake/testtask'
 class UndocumentedTestTask < Rake::TestTask
   def desc(*) end
+
+  def ruby(...)
+    env_was = ENV["JSON_COVERAGE"]
+    ENV["JSON_COVERAGE"] = "1"
+    ret = super
+    ENV["JSON_COVERAGE"] = env_was
+    ret
+  end
 end
 
 PKG_VERSION       = File.foreach(File.join(__dir__, "lib/json/version.rb")) do |line|
diff --git a/test/json/test_helper.rb b/test/json/test_helper.rb
index 24d98170..24cde434 100644
--- a/test/json/test_helper.rb
+++ b/test/json/test_helper.rb
@@ -1,19 +1,17 @@
 $LOAD_PATH.unshift(File.expand_path('../../../ext', __FILE__), File.expand_path('../../../lib', __FILE__))
 
-require 'coverage'
+if ENV["JSON_COVERAGE"]
+  # This test helper is loaded inside Ruby's own test suite, so we try to not mess it up.
+  require 'coverage'
 
-branches_supported = Coverage.respond_to?(:supported?) && Coverage.supported?(:branches)
+  branches_supported = Coverage.respond_to?(:supported?) && Coverage.supported?(:branches)
 
-# Coverage module must be started before SimpleCov to work around the cyclic require order.
-# Track both branches and lines, or else SimpleCov misleadingly reports 0/0 = 100% for non-branching files.
-Coverage.start(lines:    true,
-               branches: branches_supported)
+  # Coverage module must be started before SimpleCov to work around the cyclic require order.
+  # Track both branches and lines, or else SimpleCov misleadingly reports 0/0 = 100% for non-branching files.
+  Coverage.start(lines:    true,
+                 branches: branches_supported)
 
-begin
   require 'simplecov'
-rescue LoadError
-  # Don't fail Ruby's test suite
-else
   SimpleCov.start do
     # Enabling both coverage types to let SimpleCov know to output them together in reports
     enable_coverage :line