Optimize test client response.json()

[Adam Johnson]

It's quite common for a test to look like:

resp = self.client.get('/api/things/')
assert 'users' in resp.json()
assert 'groups' in resp.json()

Each call to json() currently re-parses the unchanged body. It could cache this :)

[Adam Johnson]

​https://github.com/django/django/pull/7584

[Tim Graham <timograham@…>]

In 19e21146:

Fixed #27516 -- Made test client's response.json() cache the parsed JSON.

[Mounir]

Sorry for revisiting this old issue.

I recently ran into trouble debugging a test. The test involved retrieving JSON results and popping keys from them via a variable:

response_data = response.json()
item1 = response_data.pop('item1')

While debugging, I was puzzled as to why the URL returned incomplete data. I had assumed that calling response.json() would return the full JSON data, but due to the caching mechanism in place, this wasn't the case.

Comparing this behaviour to the requests library, which has no caching, leads to different user expectations. Some users may find this distinction difficult to grasp.