diff --git a/tests/_client.lua b/tests/_client.lua
index 9a94fd4bd..e9f586b8e 100644
--- a/tests/_client.lua
+++ b/tests/_client.lua
@@ -3,27 +3,101 @@ local spawn = require("awful.spawn")
 -- This file provide a simple, yet flexible, test client.
 -- It is used to test the `awful.rules`
 
-return function(class, title, use_sn)
-    class = class or 'test_app'
-    title = title or 'Awesome test client'
+local test_client_source = [[
+local lgi = require 'lgi'
+local Gtk = lgi.require('Gtk')
+local Gio = lgi.require('Gio')
+Gtk.init()
 
-    local cmd = {"lua" , "-e", table.concat {
-        "local lgi = require 'lgi';",
-        "local Gtk = lgi.require('Gtk');",
-        "Gtk.init();",
-        "local class = '",class,"';",
-        "local window = Gtk.Window {",
-        "    default_width  = 100,",
-        "    default_height = 100,",
-        "    on_destroy     = Gtk.main_quit,",
-        "    title          = '",title,
-        "'};",
-        "window:set_wmclass(class, class);",
-        "window:show_all();",
-        "Gtk:main{...}"
-    }}
+local function open_window(class, title, snid)
+    local window = Gtk.Window {
+        default_width  = 100,
+        default_height = 100,
+        title          = title
+    }
+    if snid ~= "" then
+        window:set_startup_id(snid)
+    end
+    window:set_wmclass(class, class)
+    window:show_all()
+end
 
-    return spawn(cmd, use_sn)
+-- Start a coroutine for nicer input handling
+local coro = coroutine.wrap(function()
+    while true do
+        local class = coroutine.yield()
+        local title = coroutine.yield()
+        local snid = coroutine.yield()
+        open_window(class, title, snid)
+    end
+end)
+coro()
+
+-- Read lines from stdin and feed them to the coroutine
+local stdin = Gio.UnixInputStream.new(0, false)
+stdin = Gio.DataInputStream.new(stdin)
+
+local read_start, read_finish
+read_start = function()
+    stdin:read_line_async(0, nil, read_finish)
+end
+read_finish = function(...)
+    local line, length = stdin.read_line_finish(...)
+    if type(length) ~= "number" then
+        error("Error reading line: " .. tostring(length))
+    end
+
+    local eof = not line -- Behaviour of up-to-date LGI
+            or (tostring(line) == "" and #line ~= length) -- (Ab)use uninitialized variable
+    if eof then
+        Gtk.main_quit()
+    else
+        coro(tostring(line)) -- tostring() needed for older LGI versions
+        read_start()
+    end
+end
+
+read_start()
+Gtk:main{...}
+]]
+
+local lgi = require("lgi")
+local Gio = lgi.require("Gio")
+
+local initialized = false
+local pipe
+local function init()
+    if initialized then return end
+    initialized = true
+    local cmd = { "lua", "-e", test_client_source }
+    local _, _, stdin, stdout, stderr = awesome.spawn(cmd, false, true, true, true)
+    pipe = Gio.UnixOutputStream.new(stdin, true)
+    stdout = Gio.UnixInputStream.new(stdout, true)
+    stderr = Gio.UnixInputStream.new(stderr, true)
+    spawn.read_lines(stdout, function(...) print("_client", ...) end)
+    spawn.read_lines(stderr, function(...) print("_client", ...) end)
+end
+
+-- Hack needed for awesome's Startup Notification machinery
+local function get_snid(sn_rules)
+    local success, snid = spawn({ "/bin/true" }, sn_rules)
+    assert(success)
+    assert(snid)
+    return snid
+end
+
+return function(class, title, sn_rules)
+    class = class or "test_app"
+    title = title or "Awesome test client"
+
+    init()
+    local snid = sn_rules and get_snid(sn_rules) or ""
+    local data = class .. "\n" .. title .. "\n" .. snid .. "\n"
+    local success, msg = pipe:write_all(data)
+    assert(success, msg)
+
+    -- TODO: Fix the API of this function
+     return true, sn_rules and snid or nil
 end
 
 -- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80