Add coverage testing under 'tox'.

.gitignore

@@ -2,3 +2,6 @@ src/zope.dottedname.egg-info
 .tox
 *.py[co]
 docs/_build/
+.coverage
+coverage.xml
+nosetests.xml

setup.cfg

@@ -0,0 +1,6 @@
+[nosetests]
+nocapture=1
+cover-package=zope.dottedname
+cover-erase=1
+with-doctest=0
+where=src

tox.ini

@@ -1,14 +1,25 @@
 [tox]
 envlist =
-    py26,py27,py32,py33,py34,pypy,pypy3,docs
+    py26,py27,py32,py33,py34,pypy,pypy3,coverage,docs
 
 [testenv]
 commands =
-    python setup.py test -q
-# without explicit deps, setup.py test will download a bunch of eggs into $PWD
-# (and it seems I can't use zope.dottedname[testing] here, so forget DRY)
+    python setup.py -q test -q
+
+[testenv:coverage]
+basepython =
+    python2.7
+commands = 
+#   The installed version messes up nose's test discovery / coverage reporting
+#   So, we uninstall that from the environment, and then install the editable
+#   version, before running nosetests.
+    pip uninstall -q -y zope.dottedname
+    pip install -q -e .
+    nosetests --with-xunit --with-xcoverage
 deps =
-    zope.testing
+    nose
+    coverage
+    nosexcover
 
 
 [testenv:docs]
@@ -18,5 +29,4 @@ commands =
     sphinx-build -b html -d docs/_build/doctrees docs docs/_build/html
     sphinx-build -b doctest -d docs/_build/doctrees docs docs/_build/doctest
 deps =
-    {[testenv]deps}
     Sphinx