Add a functional test for addition and removal of screens

Signed-off-by: Uli Schlachter <psychon@znc.in>

tests/test-screen-changes.lua

@@ -0,0 +1,64 @@
+-- Tests for screen additions & removals
+
+local runner = require("_runner")
+local test_client = require("_client")
+local naughty = require("naughty")
+
+local real_screen = screen[1]
+local fake_screen = screen.fake_add(50, 50, 500, 500)
+local test_client1, test_client2
+
+local steps = {
+    -- Step 1: Set up some clients to experiment with and assign them as needed
+    function(count)
+        if count == 1 then  -- Setup.
+            test_client()
+            test_client()
+        end
+        local cls = client.get()
+        if #cls == 2 then
+            test_client1, test_client2 = cls[1], cls[2]
+            test_client1.screen = real_screen
+            test_client2.screen = fake_screen
+
+            -- Display a notification on the screen-to-be-removed
+            naughty.notify{ text = "test", screen = fake_screen }
+
+            return true
+        end
+    end,
+
+    -- Step 2: Say goodbye to the screen
+    function()
+        fake_screen:fake_remove()
+
+        -- TODO: This is a hack to make the test work, how to do this so that it
+        -- also works "in the wild"?
+        mypromptbox[fake_screen] = nil
+        mylayoutbox[fake_screen] = nil
+        mytaglist[fake_screen] = nil
+        mytasklist[fake_screen] = nil
+        mywibox[fake_screen] = nil
+
+        -- Wrap in a weak table to allow garbage collection
+        fake_screen = setmetatable({ fake_screen }, { __mode = "v" })
+
+        return true
+    end,
+
+    -- Step 3: Everything should now be on the main screen, the old screen
+    -- should be garbage collectable
+    function()
+        assert(test_client1.screen == real_screen, test_client1.screen)
+        assert(test_client2.screen == real_screen, test_client2.screen)
+
+        collectgarbage("collect")
+        if #fake_screen == 0 then
+            return true
+        end
+    end,
+}
+
+runner.run_steps(steps)
+
+-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80