tests/functional/test_vnc: skip test if no crypto backend available

The test_change_password test will fail if no cryptographic backend is
available (e.g. if QEMU was built on a system with no cryptographic
library development packages installed); just skip the test in that
case.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20250414093732.220498-1-cohuck@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/functional/test_vnc.py

@@ -55,6 +55,8 @@ class Vnc(QemuSystemTest):
         except VMLaunchFailure as excp:
             if "-vnc: invalid option" in excp.output:
                 self.skipTest("VNC support not available")
+            elif "Cipher backend does not support DES algorithm" in excp.output:
+                self.skipTest("No cryptographic backend available")
             else:
                 self.log.info("unhandled launch failure: %s", excp.output)
                 raise excp