allow fixture functions to be implemented as context managers:

@pytest.fixture
def myfix():
    # setup
    yield 1
    # teardown

CHANGELOG

@@ -1,4 +1,12 @@
-Changes between 2.3.4 and 2.3.5dev
+Changes between 2.3.5 and DEV
+-----------------------------------
+
+- (experimental) allow fixture functions to be 
+  implemented as context managers
+
+
+
+Changes between 2.3.4 and 2.3.5
 -----------------------------------
 
 - never consider a fixture function for test function collection

_pytest/__init__.py

@@ -1,2 +1,2 @@
 #
-__version__ = '2.3.6.dev1'
+__version__ = '2.3.6.dev2'

_pytest/python.py

@@ -1613,6 +1613,29 @@ class FixtureManager:
             except ValueError:
                 pass
 
+def call_fixture_func(fixturefunc, request, kwargs):
+    if is_generator(fixturefunc):
+        iter = fixturefunc(**kwargs)
+        next = getattr(iter, "__next__", None)
+        if next is None:
+            next = getattr(iter, "next")
+        res = next()
+        def teardown():
+            try:
+                next()
+            except StopIteration:
+                pass
+            else:
+                fs, lineno = getfslineno(fixturefunc)
+                location = "%s:%s" % (fs, lineno+1)
+                pytest.fail(
+                    "fixture function %s has more than one 'yield': \n%s" %
+                            (fixturefunc.__name__, location), pytrace=False)
+        request.addfinalizer(teardown)
+    else:
+        res = fixturefunc(**kwargs)
+    return res
+
 class FixtureDef:
     """ A container for a factory definition. """
     def __init__(self, fixturemanager, baseid, argname, func, scope, params,
@@ -1663,7 +1686,7 @@ class FixtureDef:
                         fixturefunc = fixturefunc.__get__(request.instance)
             except AttributeError:
                 pass
-            result = fixturefunc(**kwargs)
+            result = call_fixture_func(fixturefunc, request, kwargs)
         assert not hasattr(self, "cached_result")
         self.cached_result = result
         return result

setup.py

@@ -12,7 +12,7 @@ def main():
         name='pytest',
         description='py.test: simple powerful testing with Python',
         long_description = long_description,
-        version='2.3.6.dev1',
+        version='2.3.6.dev2',
         url='http://pytest.org',
         license='MIT license',
         platforms=['unix', 'linux', 'osx', 'cygwin', 'win32'],

testing/python/fixture.py

@@ -1795,3 +1795,101 @@ class TestShowFixtures:
             *hello world*
         """)
 
+
+
+class TestContextManagerFixtureFuncs:
+    def test_simple(self, testdir):
+        testdir.makepyfile("""
+            import pytest
+            @pytest.fixture
+            def arg1():
+                print ("setup")
+                yield 1
+                print ("teardown")
+            def test_1(arg1):
+                print ("test1 %s" % arg1)
+            def test_2(arg1):
+                print ("test2 %s" % arg1)
+                assert 0
+        """)
+        result = testdir.runpytest("-s")
+        result.stdout.fnmatch_lines("""
+            setup
+            test1 1
+            teardown
+            setup
+            test2 1
+            teardown
+        """)
+
+    def test_scoped(self, testdir):
+        testdir.makepyfile("""
+            import pytest
+            @pytest.fixture(scope="module")
+            def arg1():
+                print ("setup")
+                yield 1
+                print ("teardown")
+            def test_1(arg1):
+                print ("test1 %s" % arg1)
+            def test_2(arg1):
+                print ("test2 %s" % arg1)
+        """)
+        result = testdir.runpytest("-s")
+        result.stdout.fnmatch_lines("""
+            setup
+            test1 1
+            test2 1
+            teardown
+        """)
+
+    def test_setup_exception(self, testdir):
+        testdir.makepyfile("""
+            import pytest
+            @pytest.fixture(scope="module")
+            def arg1():
+                pytest.fail("setup")
+                yield 1
+            def test_1(arg1):
+                pass
+        """)
+        result = testdir.runpytest("-s")
+        result.stdout.fnmatch_lines("""
+            *pytest.fail*setup*
+            *1 error*
+        """)
+
+    def test_teardown_exception(self, testdir):
+        testdir.makepyfile("""
+            import pytest
+            @pytest.fixture(scope="module")
+            def arg1():
+                yield 1
+                pytest.fail("teardown")
+            def test_1(arg1):
+                pass
+        """)
+        result = testdir.runpytest("-s")
+        result.stdout.fnmatch_lines("""
+            *pytest.fail*teardown*
+            *1 passed*1 error*
+        """)
+
+
+    def test_yields_more_than_one(self, testdir):
+        testdir.makepyfile("""
+            import pytest
+            @pytest.fixture(scope="module")
+            def arg1():
+                yield 1
+                yield 2
+            def test_1(arg1):
+                pass
+        """)
+        result = testdir.runpytest("-s")
+        result.stdout.fnmatch_lines("""
+            *fixture function*
+            *test_yields*:2*
+        """)
+
+