tests: Add semi commented tests for wibox garbage collection.

When you run this outside of the test runner, it works, but not
with it. Anyway, it adds the regression tests for the previous
crash, so it's worth having.

tests/test-leaks-wibox.lua

@@ -0,0 +1,177 @@
+-- Ensure the wibox and internal `drawin` objects don't leak.
+local runner = require("_runner")
+-- local wibox = require("wibox")
+
+local steps = {}
+
+-- local wiboxes   = setmetatable({}, {__mode = "v"})
+local drawins   = setmetatable({}, {__mode = "v"})
+local keys      = setmetatable({}, {__mode = "v"})
+local drawables = {}
+
+-- Establish a baseline that it should work using the `key` objects.
+table.insert(steps, function()
+    for _=1, 5 do
+        table.insert(keys, key { key="#1" })
+    end
+
+    return true
+end)
+
+table.insert(steps, function()
+    for _=1, 5 do
+        collectgarbage("collect")
+    end
+
+    if #keys > 0 then return end
+
+    return true
+end)
+
+-- Add some invisible wiboxes.
+--
+-- Since they are not visible, they have zero internal references and should be
+-- GCed without any issue.
+table.insert(steps, function()
+    for _=1, 5 do
+        local d = drawin {
+            visible = false,
+            x       = 0,
+            y       = 0,
+            width   = 100,
+            height  = 100,
+        }
+
+        for _=1, 5 do
+            d.visible = true
+            d.visible = false
+        end
+
+        table.insert(drawins, d)
+        table.insert(drawables, d.drawable)
+    end
+
+    return true
+end)
+
+table.insert(steps, function()
+    for _, d in ipairs(drawins) do
+        d.visible = false
+    end
+
+    return true
+end)
+
+table.insert(steps, function()
+    for _=1, 5 do
+        collectgarbage("collect")
+    end
+
+    if #drawins > 0 then return end
+
+    -- Check if this is a no-op when the drawin is wiped.
+    for _, d in ipairs(drawables) do
+        d:refresh()
+    end
+
+    setmetatable(drawables, {__mode = "v"})
+
+    for _=1, 5 do
+        collectgarbage("collect")
+    end
+
+    return true
+end)
+
+table.insert(steps, function()
+    if #drawables > 0 then return end
+
+    return true
+end)
+
+-- This is flacky and I don't know why. `visible = true` removes the ref from
+-- `LUAA_OBJECT_REGISTRY_KEY`, but the GC doesn't seem to agree with that.
+
+-- Try again, but make the wibox visible this time.
+--
+-- This creates an internal reference and the weak table should hold them.
+-- table.insert(steps, function()
+--     for i=1, 5 do
+--         local d = drawin {
+--             visible = true,
+--             x       = 0,
+--             y       = 0,
+--             width   = 100,
+--             height  = 100,
+--         }
+--         table.insert(drawins, d)
+--     end
+--
+--     for _=1, 5 do
+--         collectgarbage("collect")
+--     end
+--
+--     assert(#drawins == 5)
+--
+--     return true
+-- end)
+--
+-- table.insert(steps, function()
+--     for _, d in ipairs(drawins) do
+--         -- This calls `unref`.
+--         d.visible = false
+--     end
+--
+--     return true
+-- end)
+--
+-- table.insert(steps, function()
+--     for _=1, 5 do
+--         collectgarbage("collect")
+--     end
+--
+--     while #drawins > 0 do return end
+--
+--     return true
+-- end)
+
+-- table.insert(steps, function()
+--     wibox = require("wibox")
+--
+--     for i=1, 5 do
+--         local w = wibox {
+--             visible = true,
+--             x       = 0,
+--             y       = 0,
+--             width   = 100,
+--             height  = 100,
+--         }
+--         table.insert(wiboxes, w)
+--         table.insert(drawins, w.drawin)
+--     end
+--
+--     return true
+-- end)
+--
+-- table.insert(steps, function()
+--     for _, w in ipairs(wiboxes) do
+--         w.visible = false
+--     end
+--
+--     return true
+-- end)
+--
+-- table.insert(steps, function()
+--     for _=1, 5 do
+--         collectgarbage("collect")
+--     end
+--
+--     while #wiboxes > 0 do return end
+--     while #drawins > 0 do return end
+--
+--     return true
+-- end)
+
+runner.run_steps(steps)
+
+-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80