shorten some test code

testing/acceptance_test.py

@@ -215,8 +215,8 @@ class TestGeneralUsage(object):
         assert not result.ret
 
     def test_issue109_sibling_conftests_not_loaded(self, testdir):
-        sub1 = testdir.tmpdir.mkdir("sub1")
-        sub2 = testdir.tmpdir.mkdir("sub2")
+        sub1 = testdir.mkdir("sub1")
+        sub2 = testdir.mkdir("sub2")
         sub1.join("conftest.py").write("assert 0")
         result = testdir.runpytest(sub2)
         assert result.ret == EXIT_NOTESTSCOLLECTED

testing/test_conftest.py

@@ -84,7 +84,7 @@ def test_conftest_in_nonpkg_with_init(tmpdir):
 
 def test_doubledash_considered(testdir):
     conf = testdir.mkdir("--option")
-    conf.join("conftest.py").ensure()
+    conf.ensure("conftest.py")
     conftest = PytestPluginManager()
     conftest_setinitial(conftest, [conf.basename, conf.basename])
     values = conftest._getconftestmodules(conf)