Replace 'raise StopIteration' usages in the code by 'return's in accordance to PEP-479

Fix #2160

CHANGELOG.rst

@@ -1,5 +1,10 @@
 3.0.7 (unreleased)
-=======================
+==================
+
+*
+
+* Replace ``raise StopIteration`` usages in the code by simple ``returns`` to finish generators, in accordance to `PEP-479`_ (`#2160`_).
+  Thanks `@tgoodlet`_ for the report and `@nicoddemus`_ for the PR.
 
 *
 
@@ -7,7 +12,9 @@
 
 *
 
-*
+.. _#2160: https://github.com/pytest-dev/pytest/issues/2160
+
+.. _PEP-479: https://www.python.org/dev/peps/pep-0479/
 
 
 3.0.6 (2017-01-22)

_pytest/python.py

@@ -174,7 +174,7 @@ def pytest_pycollect_makeitem(collector, name, obj):
     outcome = yield
     res = outcome.get_result()
     if res is not None:
-        raise StopIteration
+        return
     # nothing was collected elsewhere, let's do it here
     if isclass(obj):
         if collector.istestclass(obj, name):