tests: synchronizes the test with luakit’s internal idle queue.

- Introducing wait_for_idle() to synchronize with the internal idle
  queue. This ensures, that all code scheduled by luakit.idle_add()
  are run. For example signal connections by modules like undoclose.
- It does oes not wait for a page or tab to load like wait_for_view(..).

Tests are run faster than luakit can load (require) files. This makes
tests unreliable. It's not an issue for luakit itself, because a user
can't interract with it before the UI is loaded.

Author: c0dev0id

tests/async/test_completion.lua

@@ -6,12 +6,15 @@ local T = {}
 local assert = require("luassert")
 
 uris = {"about:blank"}
+
+local test = require("tests.lib")
 require "config.rc"
 
 local window = require "window"
 local w = assert(select(2, next(window.bywidget)))
 
 T.test_leaving_completion_restores_correct_input_text = function ()
+    test.wait_for_idle()
     local input = w.ibar.input
 
     w:enter_cmd(":tab")

tests/async/test_memory_leaks.lua

@@ -3,6 +3,8 @@
 -- @copyright 2017 Aidan Holm <aidanholm@gmail.com>
 
 uris = {"about:blank"}
+
+local test = require("tests.lib")
 require "config.rc"
 
 local window = require "window"
@@ -11,6 +13,7 @@ local w = assert(select(2, next(window.bywidget)))
 local T = {}
 
 T.test_webview_from_closed_tab_is_released = function ()
+    test.wait_for_idle()
     local refs = setmetatable({}, { __mode = "k" })
     refs[w.view] = true
     w:close_tab()

tests/async/test_scroll.lua

@@ -13,6 +13,7 @@ local window = require "window"
 local w = assert(select(2, next(window.bywidget)))
 
 T.test_scrolling_works = function ()
+    test.wait_for_idle()
     test.wait_for_view(w.view)
 
     -- Fetch height of document body

tests/async/test_undoclose.lua

@@ -15,6 +15,7 @@ local window = require "window"
 local w = assert(select(2, next(window.bywidget)))
 
 T.test_undo_close_restores_tab_history = function ()
+    test.wait_for_idle()
     -- Load page in new tab
     local uri = test.http_server() .. "undoclose_page.html"
     w:new_tab(uri)

tests/lib.lua

@@ -16,6 +16,20 @@ function _M.init(arg)
     shared_lib = arg
 end
 
+--- Pause test execution until the next idle event in the main event loop.
+--
+-- Schedules a one-shot resume callback using `luakit.idle_add()` and
+-- suspends the test coroutine until the event loop is next idle.
+-- This ensures all pending `idle_add` hooks ("post-require" module
+-- initializations) are executed before subsequent test code runs.
+--
+-- Does nothing if called outside of the test context.
+function _M.wait_for_idle()
+    local luakit = require "luakit"
+    luakit.idle_add(_M.continue)
+    _M.wait()
+end
+
 --- Pause test execution until a webview widget finishes loading.
 --
 -- @tparam widget view The webview widget to wait on.