tests/functional: Speed up the avr_mega2560 test

We can simply check for the expected pattern on the console,
no need to wait for two seconds here to search for the pattern
in the log at the end.

While we're at it, also remove the obsolete "timeout" variable
from this test.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Mark Cave-Ayland <mark.caveayland@nutanix.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20250603184710.25651-1-thuth@redhat.com>

tests/functional/test_avr_mega2560.py

@@ -18,12 +18,10 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
-import time
+from qemu_test import QemuSystemTest, Asset, wait_for_console_pattern
 
-from qemu_test import QemuSystemTest, Asset
 
 class AVR6Machine(QemuSystemTest):
-    timeout = 5
 
     ASSET_ROM = Asset(('https://github.com/seharris/qemu-avr-tests'
                        '/raw/36c3e67b8755dcf/free-rtos/Demo'
@@ -40,13 +38,12 @@ class AVR6Machine(QemuSystemTest):
         self.set_machine('arduino-mega-2560-v3')
         self.vm.add_args('-bios', rom_path)
         self.vm.add_args('-nographic')
+        self.vm.set_console()
         self.vm.launch()
 
-        time.sleep(2)
-        self.vm.shutdown()
+        wait_for_console_pattern(self,
+                        'XABCDEFGHIJKLMNOPQRSTUVWXABCDEFGHIJKLMNOPQRSTUVWXA')
 
-        self.assertIn('ABCDEFGHIJKLMNOPQRSTUVWXABCDEFGHIJKLMNOPQRSTUVWX',
-                self.vm.get_log())
 
 if __name__ == '__main__':
     QemuSystemTest.main()