bpo-40275: Use new test.support helper submodules in tests (GH-21315)

diff --git a/Lib/test/test_dbm.py b/Lib/test/test_dbm.py
index 571da97..e02d1e1 100644
--- a/Lib/test/test_dbm.py
+++ b/Lib/test/test_dbm.py
@@ -2,17 +2,18 @@
 
 import unittest
 import glob
-import test.support
+from test.support import import_helper
+from test.support import os_helper
 
 # Skip tests if dbm module doesn't exist.
-dbm = test.support.import_module('dbm')
+dbm = import_helper.import_module('dbm')
 
 try:
     from dbm import ndbm
 except ImportError:
     ndbm = None
 
-_fname = test.support.TESTFN
+_fname = os_helper.TESTFN
 
 #
 # Iterates over every database module supported by dbm currently available,
@@ -34,7 +35,7 @@
     # we don't know the precise name the underlying database uses
     # so we use glob to locate all names
     for f in glob.glob(glob.escape(_fname) + "*"):
-        test.support.unlink(f)
+        os_helper.unlink(f)
 
 
 class AnyDBMTestCase:
@@ -74,7 +75,7 @@
 
     def test_anydbm_creation_n_file_exists_with_invalid_contents(self):
         # create an empty file
-        test.support.create_empty_file(_fname)
+        os_helper.create_empty_file(_fname)
         with dbm.open(_fname, 'n') as f:
             self.assertEqual(len(f), 0)
 
@@ -169,7 +170,7 @@
         # Issue 17198: check that ndbm which is referenced in whichdb is defined
         db_file = '{}_ndbm.db'.format(_fname)
         with open(db_file, 'w'):
-            self.addCleanup(test.support.unlink, db_file)
+            self.addCleanup(os_helper.unlink, db_file)
         self.assertIsNone(self.dbm.whichdb(db_file[:-3]))
 
     def tearDown(self):
@@ -177,10 +178,10 @@
 
     def setUp(self):
         delete_files()
-        self.filename = test.support.TESTFN
+        self.filename = os_helper.TESTFN
         self.d = dbm.open(self.filename, 'c')
         self.d.close()
-        self.dbm = test.support.import_fresh_module('dbm')
+        self.dbm = import_helper.import_fresh_module('dbm')
 
     def test_keys(self):
         self.d = dbm.open(self.filename, 'c')