From 1488bad35b753901ebf7a0238e8a2c7302a35679 Mon Sep 17 00:00:00 2001
From: Samuel Williams <samuel.williams@shopify.com>
Date: Mon, 15 Jun 2026 20:27:55 +1200
Subject: [PATCH] Make ruby-coverage optional until capture starts

Move ruby-coverage from a runtime dependency to a development dependency so applications that only load integrations such as Covered::Sus do not install the native extension unless they actually record coverage.

Defer loading covered/capture from Covered::Policy#capture so requiring covered or covered/sus does not immediately require ruby/coverage. If capture is used without ruby-coverage installed, raise a targeted LoadError explaining how to add the optional dependency.

Add a Sus regression test that runs in a child process with a trap ruby/coverage file earlier on the load path. Requiring covered/sus with COVERAGE unset must not trigger that file.

Validation: PATH=/Users/samuel/.local/state/tec/profiles/base/current/global/bin:$PATH /Users/samuel/.local/state/tec/profiles/base/current/global/bin/bundle exec bake test

Validation: /Users/samuel/.local/state/tec/profiles/base/current/global/bin/bundle exec sus test/covered/sus.rb
---
 covered.gemspec        |  3 ++-
 lib/covered/capture.rb |  6 +++++-
 lib/covered/policy.rb  |  3 ++-
 test/covered/sus.rb    | 18 ++++++++++++++++++
 4 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/covered.gemspec b/covered.gemspec
index a10b22a..ad3e202 100644
--- a/covered.gemspec
+++ b/covered.gemspec
@@ -27,5 +27,6 @@ Gem::Specification.new do |spec|
 	
 	spec.add_dependency "console", "~> 1.0"
 	spec.add_dependency "msgpack", "~> 1.0"
-	spec.add_dependency "ruby-coverage", "~> 0.1"
+	
+	spec.add_development_dependency "ruby-coverage", "~> 0.1"
 end
diff --git a/lib/covered/capture.rb b/lib/covered/capture.rb
index c794129..aa2d4b1 100644
--- a/lib/covered/capture.rb
+++ b/lib/covered/capture.rb
@@ -5,7 +5,11 @@
 
 require_relative "wrapper"
 
-require "ruby/coverage"
+begin
+	require "ruby/coverage"
+rescue LoadError => error
+	raise error.exception("Covered::Capture requires the `ruby-coverage` gem. Add `gem \"ruby-coverage\", \"~> 0.1\"` to your bundle to record coverage.")
+end
 
 module Covered
 	# Captures Ruby coverage data and forwards it to another coverage output.
diff --git a/lib/covered/policy.rb b/lib/covered/policy.rb
index a2817cc..9b980c7 100644
--- a/lib/covered/policy.rb
+++ b/lib/covered/policy.rb
@@ -5,7 +5,6 @@
 
 require_relative "summary"
 require_relative "files"
-require_relative "capture"
 require_relative "persist"
 require_relative "forks"
 
@@ -67,6 +66,8 @@ def persist!(...)
 		# The runtime capture pipeline for this policy.
 		# @returns [Covered::Forks] The memoized capture pipeline.
 		def capture
+			require_relative "capture"
+			
 			@capture ||= Forks.new(
 				Capture.new(@output)
 			)
diff --git a/test/covered/sus.rb b/test/covered/sus.rb
index b897fc9..64b8a05 100644
--- a/test/covered/sus.rb
+++ b/test/covered/sus.rb
@@ -5,6 +5,11 @@
 
 require "covered/sus"
 
+require "covered/config"
+
+require "fileutils"
+require "tmpdir"
+
 describe Covered::Sus do
 	let(:coverage) do
 		Class.new do
@@ -126,4 +131,17 @@ def after_tests(assertions)
 		
 		expect(runner.covered).to be_nil
 	end
+	
+	it "does not require ruby-coverage when coverage is not requested" do
+		Dir.mktmpdir do |root|
+			FileUtils.mkdir_p(File.join(root, "ruby"))
+			File.write(File.join(root, "ruby", "coverage.rb"), "abort 'ruby-coverage was required'")
+			
+			code = <<~RUBY
+			require "covered/sus"
+			RUBY
+			
+			expect(system({"COVERAGE" => nil, "RUBYOPT" => nil}, Gem.ruby, "-Ilib", "-I#{root}", "-e", code)).to be == true
+		end
+	end
 end