[PATCH] tests/functional/m68k: Avoid ResourceWarning in the nextcube test

[Thomas Huth <thuth@redhat.com>]

From: Thomas Huth <thuth@redhat.com>

Since commit c3fd296cf7b1 ("functional: always enable all python
warnings") we enabled more warnings for the functional tests. This
triggers now a warning in the nextcube test:

 tests/functional/m68k/test_nextcube.py:47: ResourceWarning:
  unclosed file <_io.BufferedReader name='tests/functional/m68k/test_nextcube.NextCubeMachine.test_bootrom_framebuffer_size/scratch/dump.ppm'>
   width, height = Image.open(screenshot_path).size

Use a proper "with" context to avoid it.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 tests/functional/m68k/test_nextcube.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/functional/m68k/test_nextcube.py b/tests/functional/m68k/test_nextcube.py
index 13c72bd136a..c1610e58456 100755
--- a/tests/functional/m68k/test_nextcube.py
+++ b/tests/functional/m68k/test_nextcube.py
@@ -44,7 +44,8 @@ def test_bootrom_framebuffer_size(self):
         self.check_bootrom_framebuffer(screenshot_path)
 
         from PIL import Image
-        width, height = Image.open(screenshot_path).size
+        with Image.open(screenshot_path) as image:
+                width, height = image.size
         self.assertEqual(width, 1120)
         self.assertEqual(height, 832)
 
-- 
2.51.0