Test failure with 012.http due to readline(0)

[danc86]

Occasionally the gunicorn unit tests fail with an error like this:

======================================================================
FAIL: 012.http: MT: readline SZ: small_random SN: random
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib/python2.6/site-packages/nose/case.py", line 187, in runTest
    self.test(*self.arg)
  File "gunicorn-0.13.4/tests/treq.py", line 219, in test_req
    self.check(sn, sz, mt)
  File "gunicorn-0.13.4/tests/treq.py", line 229, in check
    self.same(req, sizer, matcher, cases.pop(0))
  File "gunicorn-0.13.4/tests/treq.py", line 244, in same
    t.eq(req.trailers, exp.get("trailers", []))
  File "gunicorn-0.13.4/tests/t.py", line 85, in eq
    assert a == b, "%r != %r" % (a, b)
AssertionError: [] != [('VARY', '*'), ('CONTENT-TYPE', 'text/plain')]

----------------------------------------------------------------------

I eventually narrowed it down to cases where treq.request.size_small_random was returning a sequence like [11, 0, 0]. Actually it could be any sequence which sums to 11, followed by two zeroes. Here is a reproducer:

    req = treq.request(
            os.path.join(os.path.dirname(__file__), 'requests', 'valid', '012.http'),
            treq.load_py(os.path.join(os.path.dirname(__file__), 'requests', 'valid', '012.py')))
    sizes = iter([11, 0, 0])
    req.check(req.send_all, sizes.next, req.match_readline)

The test ends up calling req.body.readline(11), which returns the complete request body 'hello world'. It then calls req.body.readline(0), which returns ''. But the test assumes it is finished reading the request, when in fact it is not. So the parser never has a chance to read the trailers, so they come out as an empty list.

I think this is an invalid test, and there's no reason to test calling body.readline(0) at all, because why would anyone do that? Here is a simple patch to stop testing with zero:

--- gunicorn-0.13.4/tests/treq.py   2011-08-22 05:11:35.000000000 +1000
+++ gunicorn-0.13.4.patched/tests/treq.py   2012-01-31 13:28:37.687182655 +1000
@@ -97,7 +97,7 @@
         return 1

     def size_small_random(self):
-        return random.randint(0, 4)
+        return random.randint(1, 4)

     def size_random(self):
         return random.randint(1, 4096)

[benoitc]

@davisp Thoughts?