How to create functional tests for Django view

In my Django app, I have a view which makes a request to an API server to retrieve data, then displays this data back in a template.

I am completely new to testing, and am unsure about what functional tests I can create to test this view. I have created a test to assert that the popup loads and returns a HTTP response 200 (mocking out the API and using a pre-defined mock data set). How else can I test this view? How can I test whether the view is loading the correct data?