[test_compat] Use compat_setenv

test/test_compat.py

@@ -27,9 +27,7 @@ from youtube_dl.compat import (
 class TestCompat(unittest.TestCase):
     def test_compat_getenv(self):
         test_str = 'тест'
-        os.environ['YOUTUBE-DL-TEST'] = (
+        compat_setenv('YOUTUBE-DL-TEST', test_str)
-            test_str if sys.version_info >= (3, 0)
-            else test_str.encode(get_filesystem_encoding()))
         self.assertEqual(compat_getenv('YOUTUBE-DL-TEST'), test_str)
 
     def test_compat_setenv(self):
@@ -42,11 +40,9 @@ class TestCompat(unittest.TestCase):
     def test_compat_expanduser(self):
         old_home = os.environ.get('HOME')
         test_str = 'C:\Documents and Settings\тест\Application Data'
-        os.environ['HOME'] = (
+        compat_setenv('HOME', test_str)
-            test_str if sys.version_info >= (3, 0)
-            else test_str.encode(get_filesystem_encoding()))
         self.assertEqual(compat_expanduser('~'), test_str)
-        os.environ['HOME'] = old_home
+        compat_setenv('HOME', old_home)
 
     def test_all_present(self):
         import youtube_dl.compat