New testing module (#774)

Introducing a new testing module to replace the external gems
`phlex-testing-capybara` and `phlex-testing-nokogiri`.

lib/phlex/testing.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+require "phlex"
+
+module Phlex::Testing
+	autoload :SGML, "phlex/testing/sgml"
+	autoload :Capybara, "phlex/testing/capybara"
+	autoload :Nokogiri, "phlex/testing/nokogiri"
+	autoload :Nokolexbor, "phlex/testing/nokolexbor"
+end

lib/phlex/testing/capybara.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+require "capybara"
+
+module Phlex::Testing::Capybara
+	include Phlex::Testing::SGML
+
+	def self.included(mod)
+		if defined?(Minitest::Test) && Minitest::Test > mod
+			require "capybara/minitest"
+			include Capybara::Minitest::Assertions
+		end
+
+		if defined?(RSpec::Core::ExampleGroup) && RSpec::Core::ExampleGroup > mod
+			require "capybara/rspec"
+			include Capybara::RSpecMatchers
+		end
+	end
+
+	attr_reader :page
+	alias_method :component, :page
+
+	def render(...)
+		@page = ::Capybara::Node::Simple.new(
+			render_to_string(...),
+		)
+	end
+end

lib/phlex/testing/nokogiri.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require "nokogiri"
+
+module Phlex::Testing::Nokogiri
+	include Phlex::Testing::SGML
+
+	def render_fragment(...)
+		::Nokogiri::HTML5.fragment(
+			render_to_string(...),
+		)
+	end
+
+	def render_document(...)
+		::Nokogiri::HTML5(
+			render_to_string(...),
+		)
+	end
+end

lib/phlex/testing/nokolexbor.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require "nokolexbor"
+
+module Phlex::Testing::Nokolexbor
+	include Phlex::Testing::SGML
+
+	def render_fragment(...)
+		Nokolexbor::DocumentFragment.parse(
+			render_to_string(...),
+		)
+	end
+
+	def render_document(...)
+		::Nokolexbor::HTML(
+			render_to_string(...),
+		)
+	end
+end

lib/phlex/testing/sgml.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+module Phlex::Testing::SGML
+	def render_to_string(component, &)
+		component.call(view_context:, &)
+	end
+
+	def view_context = nil
+end