From 18150e0d78abfacfdff71f3ffa0e3aaf70d196ad Mon Sep 17 00:00:00 2001
From: Robin Miller <robin@tenjin.ca>
Date: Wed, 10 Sep 2025 15:57:37 -0600
Subject: [PATCH 1/2] Enable coverage for all files and add branch coverage
 tracking.

---
 test/json/test_helper.rb | 39 ++++++++++++++++++++++++++++++---------
 1 file changed, 30 insertions(+), 9 deletions(-)

diff --git a/test/json/test_helper.rb b/test/json/test_helper.rb
index cf592deb..52938915 100644
--- a/test/json/test_helper.rb
+++ b/test/json/test_helper.rb
@@ -1,14 +1,6 @@
 $LOAD_PATH.unshift(File.expand_path('../../../ext', __FILE__), File.expand_path('../../../lib', __FILE__))
 
-begin
-  require 'simplecov'
-rescue LoadError
-  # Don't fail Ruby's test suite
-else
-  SimpleCov.start
-end
-
-require 'json'
+require "coverage"
 require 'test/unit'
 
 if ENV["JSON_COMPACT"]
@@ -35,3 +27,32 @@
   require "core_assertions"
   Test::Unit::TestCase.include Test::Unit::CoreAssertions
 end
+
+Test::Unit.at_exit do
+  begin
+    require 'simplecov'
+  rescue LoadError
+    # Don't fail Ruby's test suite
+  else
+    # Force SimpleCov to include all files in its report, avoiding accidental require-order misses
+    SimpleCov.track_files 'lib/**/*.rb'
+
+    SimpleCov.add_filter 'lib/json/truffle_ruby' unless RUBY_ENGINE == 'truffleruby'
+
+    SimpleCov.enable_coverage :branch
+    SimpleCov.primary_coverage :branch
+
+    # must be true for SimpleCov to generate a result at all
+    SimpleCov.running = true
+    coverage = SimpleCov.result
+
+    SimpleCov.write_last_run(coverage)
+    coverage.format!
+  end
+end
+
+# Start built-in Coverage directly because SimpleCov depends on JSON gem, wrecking the require order.
+# SimpleCov is still used for the pretty formatting afterward.
+# require is at end of file to avoid coverage monitoring any irrelevant code (eg. Test::Unit)
+Coverage.start(lines: true, branches: true)
+require 'json'

From 11dde98afa685ea80d980352f6905b1adf9e0fdd Mon Sep 17 00:00:00 2001
From: Robin Miller <robin@tenjin.ca>
Date: Wed, 10 Sep 2025 17:05:18 -0600
Subject: [PATCH 2/2] Use a require prepend in testing to prevent circular
 require breaking SimpleCov

---
 test/json/test_helper.rb | 55 +++++++++++++++++++++++++---------------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/test/json/test_helper.rb b/test/json/test_helper.rb
index 52938915..5d230037 100644
--- a/test/json/test_helper.rb
+++ b/test/json/test_helper.rb
@@ -1,6 +1,5 @@
 $LOAD_PATH.unshift(File.expand_path('../../../ext', __FILE__), File.expand_path('../../../lib', __FILE__))
 
-require "coverage"
 require 'test/unit'
 
 if ENV["JSON_COMPACT"]
@@ -28,31 +27,45 @@
   Test::Unit::TestCase.include Test::Unit::CoreAssertions
 end
 
-Test::Unit.at_exit do
-  begin
-    require 'simplecov'
-  rescue LoadError
-    # Don't fail Ruby's test suite
-  else
-    # Force SimpleCov to include all files in its report, avoiding accidental require-order misses
-    SimpleCov.track_files 'lib/**/*.rb'
+# The built-in Coverage module (and therefore SimpleCov) need to be activated prior to any require statements.
+# But! SimpleCov requires 'json' before activating Coverage measurement, meaning it misses several files.
+#
+# The solution is to defer any JSON requires from SimpleCov, which works out because we require it ourselves before
+# SimpleCov actually uses it for anything.
+module JSONTestPatch
+  def require(name)
+    if name == 'json'
+      caller_path = caller_locations.first.path
+
+      return false if caller_path.match? %r(/simplecov/)
+    end
+
+    super(name)
+  end
+end
+Kernel.prepend JSONTestPatch
 
-    SimpleCov.add_filter 'lib/json/truffle_ruby' unless RUBY_ENGINE == 'truffleruby'
+begin
+  require 'simplecov'
+rescue LoadError
+  # Don't fail Ruby's test suite
+else
+  # Override default at_exit or else it will fire when the Rake task process ends early
+  SimpleCov.external_at_exit = true
+  Test::Unit.at_exit do
+    SimpleCov.at_exit_behavior
+  end
 
-    SimpleCov.enable_coverage :branch
-    SimpleCov.primary_coverage :branch
+  SimpleCov.start do
+    # Force SimpleCov to include all files in its report, avoiding accidental require-order misses
+    track_files 'lib/**/*.rb'
 
-    # must be true for SimpleCov to generate a result at all
-    SimpleCov.running = true
-    coverage = SimpleCov.result
+    add_filter 'lib/json/truffle_ruby' unless RUBY_ENGINE == 'truffleruby'
 
-    SimpleCov.write_last_run(coverage)
-    coverage.format!
+    enable_coverage :branch
+    primary_coverage :branch
   end
 end
 
-# Start built-in Coverage directly because SimpleCov depends on JSON gem, wrecking the require order.
-# SimpleCov is still used for the pretty formatting afterward.
-# require is at end of file to avoid coverage monitoring any irrelevant code (eg. Test::Unit)
-Coverage.start(lines: true, branches: true)
+# Require must be after SimpleCov is started for it to see the code
 require 'json'