The client_test5.py line 772 checks whether the topic alias is set for the initial publish being received. However, according to 3.3.2.3.4 " It sets a Topic Alias mapping by including a non-zero length Topic Name and a Topic Alias in the PUBLISH packet. "
This implies that the first time a topic alias is set, the topic name still needs to be specified. Otherwise clients cannot know the mapping.
The client_test5.py line 772 checks whether the topic alias is set for the initial publish being received. However, according to 3.3.2.3.4 " It sets a Topic Alias mapping by including a non-zero length Topic Name and a Topic Alias in the PUBLISH packet. " This implies that the first time a topic alias is set, the topic name still needs to be specified. Otherwise clients cannot know the mapping.