Run the tests in optimized mode too to ensure that things still work

without assertions.

Fix one assert that should have been a runtime error (there are probably
more, but this is the only one currently covered by the test suite).

.gitignore

@@ -1,4 +1,5 @@
 *.pyc
+*.pyo
 *.so
 *.class
 *~

tornado/simple_httpclient.py

@@ -364,8 +364,10 @@ def _on_headers(self, data):
         if 100 <= self.code < 200 or self.code in (204, 304):
             # These response codes never have bodies
             # http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.3
-            assert "Transfer-Encoding" not in self.headers
-            assert content_length in (None, 0)
+            if ("Transfer-Encoding" in self.headers or
+                content_length not in (None, 0)):
+                raise ValueError("Response with code %d should not have body" %
+                                 self.code)
             self._on_body(b(""))
             return
 

tox.ini

@@ -13,7 +13,7 @@
 [tox]
 # "-full" variants include optional dependencies, to ensure
 # that things work both in a bare install and with all the extras.
-envlist = py27-full, py27-curl, py25-full, py32, pypy, py25, py26, py26-full, py27, py32-utf8, py33
+envlist = py27-full, py27-curl, py25-full, py32, pypy, py25, py26, py26-full, py27, py32-utf8, py33, py27-opt, py32-opt
 [testenv]
 commands = python -m tornado.test.runtests {posargs:}
 
@@ -87,3 +87,19 @@ setenv = LANG=en_US.utf-8
 [testenv:py33]
 # tox doesn't yet know "py33" by default
 basepython = python3.3
+
+# Python's optimized mode disables the assert statement, so run the
+# tests in this mode to ensure we haven't fallen into the trap of relying
+# on an assertion's side effects or using them for things that should be
+# runtime errors.
+[testenv:py27-opt]
+basepython = python2.7
+deps =
+     MySQL-python
+     pycurl
+     twisted>=12.0.0
+commands = python -O -m tornado.test.runtests {posargs:}
+
+[testenv:py32-opt]
+basepython = python3.2
+commands = python -O -m tornado.test.runtests {posargs:}