fix(test): actually assert error msg in test_api_mmds_config

Make the test actually assert that the returned error matches the error
message stored in a local variable.

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

tests/integration_tests/functional/test_api.py

@@ -250,7 +250,7 @@ def test_api_mmds_config(uvm_plain):
         "The list of network interface IDs that allow "
         "forwarding MMDS requests is empty."
     )
-    with pytest.raises(RuntimeError):
+    with pytest.raises(RuntimeError, match=err_msg):
         test_microvm.api.mmds_config.put(network_interfaces=[])
 
     # Setting MMDS config when no network device has been attached