Fix autouse fixtures defined in a TestCase subclass

CHANGELOG

@@ -12,6 +12,10 @@
 - preserve warning functions after call to pytest.deprecated_call. Thanks
   Pieter Mulder for PR.
 
+- fix issue854: autouse yield_fixtures defined as class members of
+  unittest.TestCase subclasses now work as expected.
+  Thannks xmo-odoo for the report and Bruno Oliveira for the PR.
+
 - fix issue833: --fixtures now shows all fixtures of collected test files, instead of just the
   fixtures declared on the first one.
   Thanks Florian Bruhin for reporting and Bruno Oliveira for the PR.

_pytest/python.py

@@ -1900,10 +1900,13 @@ class FixtureDef:
             self.finish()
             assert not hasattr(self, "cached_result")
 
-        if self.unittest:
-            result = self.func(request.instance, **kwargs)
-        else:
         fixturefunc = self.func
+
+        if self.unittest:
+            if request.instance is not None:
+                # bind the unbound method to the TestCase instance
+                fixturefunc = self.func.__get__(request.instance)
+        else:
             # the fixture function needs to be bound to the actual
             # request.instance so that code working with "self" behaves
             # as expected.
@@ -1911,6 +1914,7 @@ class FixtureDef:
                 fixturefunc = getimfunc(self.func)
                 if fixturefunc != self.func:
                     fixturefunc = fixturefunc.__get__(request.instance)
+
         try:
             result = call_fixture_func(fixturefunc, request, kwargs,
                                        self.yieldctx)

testing/test_unittest.py

@@ -607,18 +607,23 @@ def test_unittest_unexpected_failure(testdir):
     ])
 
 
-
+@pytest.mark.parametrize('fix_type, stmt', [
-def test_unittest_setup_interaction(testdir):
+    ('fixture', 'return'),
+    ('yield_fixture', 'yield'),
+])
+def test_unittest_setup_interaction(testdir, fix_type, stmt):
     testdir.makepyfile("""
         import unittest
         import pytest
         class MyTestCase(unittest.TestCase):
-            @pytest.fixture(scope="class", autouse=True)
+            @pytest.{fix_type}(scope="class", autouse=True)
             def perclass(self, request):
                 request.cls.hello = "world"
-            @pytest.fixture(scope="function", autouse=True)
+                {stmt}
+            @pytest.{fix_type}(scope="function", autouse=True)
             def perfunction(self, request):
                 request.instance.funcname = request.function.__name__
+                {stmt}
 
             def test_method1(self):
                 assert self.funcname == "test_method1"
@@ -629,7 +634,7 @@ def test_unittest_setup_interaction(testdir):
 
             def test_classattr(self):
                 assert self.__class__.hello == "world"
-    """)
+    """.format(fix_type=fix_type, stmt=stmt))
     result = testdir.runpytest()
     result.stdout.fnmatch_lines("*3 passed*")