MQTT sensor won't show as entity

Configuration
1

I created a basic string in MQTT which I intend on converting into a sensor at some point, my issue is that it isn’t showing as a sensor under Home Assistant.

Here is the code in configuration.ymal

mqtt:
  broker: "(The IP of the server sending is here)"
  port: (The port that it is sending on)

sensor:
  - platform: mqtt
    name: "TestSensor"
    state_topic: "test"

The name of the topic that I am posting to is simply “test”.
It shows up all fine under “integrations” but not as an entity