All classes now subclass object for better py3 compatibility

Fix #2147

testing/acceptance_test.py

@@ -901,7 +901,7 @@ def test_deferred_hook_checking(testdir):
     testdir.syspathinsert()
     testdir.makepyfile(**{
         'plugin.py': """
-        class Hooks:
+        class Hooks(object):
             def pytest_my_hook(self, config):
                 pass
 

testing/python/collect.py

@@ -880,10 +880,10 @@ class TestConftestCustomization(object):
             import sys, os, imp
             from _pytest.python import Module
 
-            class Loader:
+            class Loader(object):
                 def load_module(self, name):
                     return imp.load_source(name, name + ".narf")
-            class Finder:
+            class Finder(object):
                 def find_module(self, name, path=None):
                     if os.path.exists(name + ".narf"):
                         return Loader()

testing/python/fixture.py

@@ -2828,7 +2828,7 @@ class TestShowFixtures(object):
     def test_show_fixtures_indented_in_class(self, testdir):
         p = testdir.makepyfile(dedent('''
             import pytest
-            class TestClass:
+            class TestClass(object):
                 @pytest.fixture
                 def fixture1(self):
                     """line1

testing/python/metafunc.py

@@ -241,7 +241,7 @@ class TestMetafunc(object):
         """
         from _pytest.python import _idval
 
-        class TestClass:
+        class TestClass(object):
             pass
 
         def test_function():

testing/test_capture.py

@@ -1245,7 +1245,7 @@ def test_py36_windowsconsoleio_workaround_non_standard_streams():
     """
     from _pytest.capture import _py36_windowsconsoleio_workaround
 
-    class DummyStream:
+    class DummyStream(object):
         def write(self, s):
             pass
 

testing/test_pytester.py

@@ -135,7 +135,7 @@ def test_makepyfile_utf8(testdir):
     assert u"mixed_encoding = u'São Paulo'".encode('utf-8') in p.read('rb')
 
 
-class TestInlineRunModulesCleanup:
+class TestInlineRunModulesCleanup(object):
     def test_inline_run_test_module_not_cleaned_up(self, testdir):
         test_mod = testdir.makepyfile("def test_foo(): assert True")
         result = testdir.inline_run(str(test_mod))
@@ -146,7 +146,7 @@ class TestInlineRunModulesCleanup:
         assert result2.ret == EXIT_TESTSFAILED
 
     def spy_factory(self):
-        class SysModulesSnapshotSpy:
+        class SysModulesSnapshotSpy(object):
             instances = []
 
             def __init__(self, preserve=None):
@@ -223,7 +223,7 @@ def test_inline_run_clean_sys_paths(testdir):
         assert sys.meta_path == original_meta_path
 
     def spy_factory(self):
-        class SysPathsSnapshotSpy:
+        class SysPathsSnapshotSpy(object):
             instances = []
 
             def __init__(self):
@@ -266,7 +266,7 @@ def test_cwd_snapshot(tmpdir):
     assert py.path.local() == foo
 
 
-class TestSysModulesSnapshot:
+class TestSysModulesSnapshot(object):
     key = 'my-test-module'
 
     def test_remove_added(self):
@@ -329,7 +329,7 @@ class TestSysModulesSnapshot:
 
 
 @pytest.mark.parametrize('path_type', ('path', 'meta_path'))
-class TestSysPathsSnapshot:
+class TestSysPathsSnapshot(object):
     other_path = {
         'path': 'meta_path',
         'meta_path': 'path'}

testing/test_terminal.py

@@ -966,7 +966,7 @@ def test_no_trailing_whitespace_after_inifile_word(testdir):
     assert 'inifile: tox.ini\n' in result.stdout.str()
 
 
-class TestProgress:
+class TestProgress(object):
 
     @pytest.fixture
     def many_tests_files(self, testdir):
@@ -1047,7 +1047,7 @@ class TestProgress:
         ])
 
 
-class TestProgressWithTeardown:
+class TestProgressWithTeardown(object):
     """Ensure we show the correct percentages for tests that fail during teardown (#3088)"""
 
     @pytest.fixture