testing Client support for middleware

[Henrik Vendelbo]

I propose the following improvement:

The testing client is great for testing the whole request chain.
If you want to test the middleware part of the request, you need
to either,
1) Doing a regular request with an added middleware instance for
testing the request object.
2) Directly call one or more middleware instances passing a request
and response.

If your middleware sets a host_name attribute on the request object you can test it this way:

from django.test import Client,LastRequestMiddleware
...
def test_host_name(self):
    lrm = LastRequestMiddleware()
    c = Client(middleware_instances = [lrm])
    response = c.get('/')
    assert haskey(lrm.request,"host_name"), "The host name was not set"

Using this approach you can add any custom middleware to the chain.

If you want to test your middleware without relying on the url resolution and views
working, you can invoke a simplified handler that returns a blank response in place
of calling the view.

c = Client() 
mym = MyMiddleware()
response = c.get('/',only_middleware=[mym]) 
assert 'RESULT' in response, "RESULT header not added to response"

Calling the client this was means that the middleware classes from settings are not called,
but only the ones you specify by passing the list of instances.

[Henrik Vendelbo]

Patch without docs

[Carl Meyer]

There are a whole host of other settings besides MIDDLEWARE_CLASSES that one _might_ want to change temporarily for a test; adding them all as keyword args to the test client is ugly.

You can just change/set the actual setting and then revert after your test; see ​http://www.djangosnippets.org/snippets/1011/ for a snippet to make that easy.

Not resolving since I'm not a triager (someone higher up tell me if I should've just gone ahead and resolved this), but almost certain this is a wontfix.

[Russell Keith-Magee]

Replying to carljm:

Not resolving since I'm not a triager (someone higher up tell me if I should've just gone ahead and resolved this), but almost certain this is a wontfix.

Right on the money.

If you want to test middleware, test the middleware. A middleware is just two methods on a class; if you want to test the middleware, call those functions from your tests. Munging the entire test client to make it "easier" to invoke those methods is entirely the wrong way to go.

The only complication is that faking a request object to pass to the middleware method isn't completely trivial. The solution, therefore, is to make it easier to create a request object. #9002 contains a proposal for doing this that doesn't require so much duct tape.

On a completely procedural note - the patch also needs tests. As Malcolm noted in his DjangoCon talk - submitting a patch without tests is shorthand for "Here are some bugs I thought you should have". If you want your contributions to be taken seriously, write the tests first.

[anonymous@…]

@carljm - Nice, so it's not important to be able to test your whole stack at once? That's one of the most idiotic things I've ever read. Middleware is just 2 methods, just like any other 2 methods in your software. Why don't we just write tests for 2 methods at a time and never bother to check that things work together, let alone don't regress, idiot.