Initial, simple, unit-tested implementation of QMPClient.

This follows the README given earlier, at least in principle, but
doesn't implement the entirety of QMP, by any stretch of the
imagination.

Notable by their absence are error responses, argument validation
(for incoming and outgoing messsages of all types), and any visibility
into qmp_capabilities.

Also missing are integration tests.

test/unit/test_qmp_client.rb

@@ -0,0 +1,82 @@
+require 'helper'
+require 'qmp_client'
+
+module TestQMPClient
+  class TestModuleMethods < BaseTestCase
+
+    include QMPClient
+
+    def test_require_loads_main_constants
+      assert(defined?(::QMPClient), "QMPClient not defined")
+      assert(defined?(::QMPClient::API), "QMPClient::API not defined")
+      assert(defined?(::QMPClient::Connectors), "Connectors not defined")
+      assert(defined?(::QMPClient::Connectors::Socket), "Socket connector not defined")
+      assert(defined?(::QMPClient::Connectors::WriteProxy), "WriteProxy not defined")
+      assert(defined?(::QMPClient::Messages), "Messages module not defined")
+      assert(defined?(::QMPClient::Messages::Query), "Query message not defined")
+      assert(defined?(::QMPClient::Messages::Command), "Command message not defined")
+      assert(defined?(::QMPClient::Messages::Event), "Event message not defined")
+      assert(defined?(::QMPClient::Messages::Reply), "Greeting message not defined")
+    end
+
+    def expects_socket_run(rio, wio=nil)
+      rq, wq = [Queue.new, Queue.new]
+      Connectors::Socket.any_instance.expects(:run).with(rio, wio).
+        once.yields(rq, wq)
+      API.expects(:run).with(rq, wq).once.yields("(mock-api)")
+    end
+
+    def test_connect_tcp
+      cargs = ["127.0.0.1", 4440, "127.0.0.1", 40000]
+      mock_sock = mock("(tcp-socket)")
+      mock_sock.stubs(:closed? => false, :close => true)
+      TCPSocket.expects(:connect).with(*cargs).once.returns(mock_sock)
+      expects_socket_run(mock_sock)
+
+      runs_api_block = false
+      QMPClient::connect_tcp(*cargs) do |api|
+        runs_api_block = true
+      end
+
+      assert(runs_api_block, "API not yielded by connect_tcp")
+    end
+
+    def test_connect_unix
+      mock_sock = mock("(unix-socket)")
+      mock_sock.stubs(:closed? => false, :close => true)
+      UNIXSocket.expects(:connect).with("/tmp/test.sock").once.returns(mock_sock)
+
+      expects_socket_run(mock_sock)
+
+      runs_api_block = false
+      QMPClient::connect_unix("/tmp/test.sock") do |api|
+        runs_api_block = true
+      end
+
+      assert(runs_api_block, "API not yielded by connect_unix")
+    end
+
+    def test_connect_socket
+      rs, ws = [mock("(read-socket)"), mock("(write-socket)")]
+      expects_socket_run(rs, ws)
+
+      runs_api_block = false
+      QMPClient::connect_socket(rs, ws) do |api|
+        runs_api_block = true
+      end
+
+      assert(runs_api_block, "API not yielded by connect_socket")
+
+      # If we pass in just one socket, it's used for both read and write
+      rw = mock("(rw-socket)")
+      runs_api_block = false
+      expects_socket_run(rw)
+
+      QMPClient::connect_socket(rw) do
+        runs_api_block = true
+      end
+      assert(runs_api_block, "API not yielded by connect_socket with one sock")
+    end
+
+  end
+end