Hi @Anna Kozorovitsky ,
I created default client with WebApplicationFactory that sends requests to "manager" webAPI. My question is how can I test that "notify" webAPI got a response from the server by post request in the controller.
According to your description, I suggest you could try to follow this article to use the WebApplicationFactory to create the test server for integration tests. By using this class, you could create the client and set the url to test it.