Use zope-testrunner in tox.

tox.ini

 [tox]
 envlist =
-    py26,py27,py32,py33
+    py26,py27,py32,py33,simple
 
 [testenv]
 commands =
-    python setup.py test -q
+# Run unit tests first.
+    zope-testrunner -u --test-path=src --auto-color --auto-progress
+# Only run functional tests if unit tests pass.
+    zope-testrunner -f -j99 --test-path=src --auto-color --auto-progress
 deps =
-    ZODB >= 4.0.0b1
+    ZODB >= 4.0.0b2
     random2
     ZConfig
     manuel
@@ -16,3 +19,12 @@ deps =
     zdaemon
     zope.interface
     zope.testing
+    zope.testrunner
+
+[testenv:simple]
+# Test that 'setup.py test' works
+basepython =
+    python2.7
+commands =
+    python setup.py test -q
+deps = {[testenv]deps}