tests: add testcase for #239, bug number 2

If a window is unmapped during the draw_callback re-run when the screen
is just redirected, that window won't get a chance to acquire a pixmap.
If fading is enabled, the compositor will try to render that window and
crash.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

tests/configs/issue239_2.conf

@@ -0,0 +1,8 @@
+fading = true;
+fade-in-step = 1;
+fade-out-step = 0.01;
+shadow = true;
+shadow-exclude = [
+"name = 'NoShadow'"
+]
+unredir-if-possible = true;

tests/run_tests.sh

@@ -5,3 +5,4 @@ cd $(dirname $0)
 
 ./run_one_test.sh $compton configs/empty.conf testcases/basic.py
 ./run_one_test.sh $compton configs/issue239.conf testcases/issue239.py
+./run_one_test.sh $compton configs/issue239_2.conf testcases/issue239_2.py

tests/testcases/issue239_2.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python
+
+import xcffib.xproto as xproto
+import xcffib
+import time
+
+conn = xcffib.connect()
+setup = conn.get_setup()
+root = setup.roots[0].root
+visual = setup.roots[0].root_visual
+depth = setup.roots[0].root_depth
+
+# issue 239 is caused by a window gaining a shadow during its fade-out transition
+wid = conn.generate_id()
+print("Window ids are ", hex(wid))
+
+# Create a window
+mask = xproto.CW.BackPixel
+value = [ setup.roots[0].white_pixel ]
+conn.core.CreateWindowChecked(depth, wid, root, 0, 0, 100, 100, 0, xproto.WindowClass.InputOutput, visual, mask, value).check()
+
+name = "_NET_WM_STATE"
+name_atom = conn.core.InternAtom(False, len(name), name).reply().atom
+atom = "ATOM"
+atom_atom = conn.core.InternAtom(False, len(atom), atom).reply().atom
+fs = "_NET_WM_STATE_FULLSCREEN"
+fs_atom = conn.core.InternAtom(False, len(fs), fs).reply().atom
+
+
+# Map the window
+conn.core.MapWindowChecked(wid).check()
+
+time.sleep(0.5)
+
+conn.core.ChangePropertyChecked(xproto.PropMode.Replace, wid, name_atom, atom_atom, 32, 1, [fs_atom]).check()
+
+time.sleep(0.5)
+
+conn.core.ChangePropertyChecked(xproto.PropMode.Replace, wid, name_atom, atom_atom, 32, 0, []).check()
+
+conn.core.GetInputFocus().reply()
+
+# Unmap the window
+conn.core.UnmapWindowChecked(wid).check()
+
+time.sleep(0.5)
+
+# Destroy the window
+conn.core.DestroyWindowChecked(wid).check()