Add PortHelpers from SpaceShoes with one simple test (#558)

scarpe-components/lib/scarpe/components/port_helpers.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+require "socket"
+
+module Scarpe::Components
+  module PortHelpers
+    MAX_SERVER_STARTUP_WAIT = 5.0
+
+    def port_working?(ip, port_num)
+      begin
+        TCPSocket.new(ip, port_num)
+      rescue Errno::ECONNREFUSED
+        return false
+      end
+      return true
+    end
+
+    def wait_until_port_working(ip, port_num, max_wait: MAX_SERVER_STARTUP_WAIT)
+      t_start = Time.now
+      loop do
+        if Time.now - t_start > max_wait
+          raise "Server on port #{port_num} didn't start up in time!"
+        end
+
+        sleep 0.1
+        return if port_working?(ip, port_num)
+      end
+    end
+  end
+end

scarpe-components/test/test_port_helpers.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+require_relative "test_helper"
+
+require "scarpe/components/port_helpers"
+class TestPortHelpers < Minitest::Test
+  include Scarpe::Components::PortHelpers
+
+  def test_port_finder
+    assert_equal false, port_working?("127.0.0.1", 9832), "Port 9832 should be unused!"
+  end
+end