Clean up NEWS entry and tests for shutil.disk_usage (#12442)

Doc/whatsnew/3.3.rst

@@ -206,7 +206,7 @@ handle NAT with non-secure FTP without opening fixed ports.
 shutil
 ------
 
-The :mod:`shutil` module has a new :func:`~shutil.disk_usage` providing total,
+The :mod:`shutil` module has a new :func:`~shutil.disk_usage` function providing total,
 used and free disk space statistics.
 
 (Contributed by Giampaolo Rodolà in :issue:`12442`)

Lib/test/test_shutil.py

@@ -732,11 +732,11 @@ class TestShutil(unittest.TestCase):
                          "disk_usage not available on this platform")
     def test_disk_usage(self):
         usage = shutil.disk_usage(os.getcwd())
-        self.assertTrue(usage.total > 0)
-        self.assertTrue(usage.used > 0)
-        self.assertTrue(usage.free >= 0)
-        self.assertTrue(usage.total >= usage.used)
-        self.assertTrue(usage.total > usage.free)
+        self.assertGreater(usage.total, 0)
+        self.assertGreater(usage.used, 0)
+        self.assertGreaterEqual(usage.free, 0)
+        self.assertGreaterEqual(usage.total, usage.used)
+        self.assertGreater(usage.total, usage.free)
 
 
 class TestMove(unittest.TestCase):