Make ruby-coverage optional until capture starts

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

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.

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)
 			)

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