bpo-40275: Use new test.support helper submodules in tests (GH-21317)

diff --git a/Lib/test/test_marshal.py b/Lib/test/test_marshal.py
index b7f4dbb..7bcf8e8 100644
--- a/Lib/test/test_marshal.py
+++ b/Lib/test/test_marshal.py
@@ -1,4 +1,5 @@
 from test import support
+from test.support import os_helper
 import array
 import io
 import marshal
@@ -17,13 +18,13 @@
         new = marshal.loads(marshal.dumps(sample, *extra))
         self.assertEqual(sample, new)
         try:
-            with open(support.TESTFN, "wb") as f:
+            with open(os_helper.TESTFN, "wb") as f:
                 marshal.dump(sample, f, *extra)
-            with open(support.TESTFN, "rb") as f:
+            with open(os_helper.TESTFN, "rb") as f:
                 new = marshal.load(f)
             self.assertEqual(sample, new)
         finally:
-            support.unlink(support.TESTFN)
+            os_helper.unlink(os_helper.TESTFN)
 
 class IntTestCase(unittest.TestCase, HelperMixin):
     def test_ints(self):
@@ -281,20 +282,20 @@
             ilen = len(interleaved)
             positions = []
             try:
-                with open(support.TESTFN, 'wb') as f:
+                with open(os_helper.TESTFN, 'wb') as f:
                     for d in data:
                         marshal.dump(d, f)
                         if ilen:
                             f.write(interleaved)
                         positions.append(f.tell())
-                with open(support.TESTFN, 'rb') as f:
+                with open(os_helper.TESTFN, 'rb') as f:
                     for i, d in enumerate(data):
                         self.assertEqual(d, marshal.load(f))
                         if ilen:
                             f.read(ilen)
                         self.assertEqual(positions[i], f.tell())
             finally:
-                support.unlink(support.TESTFN)
+                os_helper.unlink(os_helper.TESTFN)
 
     def test_loads_reject_unicode_strings(self):
         # Issue #14177: marshal.loads() should not accept unicode strings
@@ -516,81 +517,81 @@
 
     def test_write_long_to_file(self):
         for v in range(marshal.version + 1):
-            _testcapi.pymarshal_write_long_to_file(0x12345678, support.TESTFN, v)
-            with open(support.TESTFN, 'rb') as f:
+            _testcapi.pymarshal_write_long_to_file(0x12345678, os_helper.TESTFN, v)
+            with open(os_helper.TESTFN, 'rb') as f:
                 data = f.read()
-            support.unlink(support.TESTFN)
+            os_helper.unlink(os_helper.TESTFN)
             self.assertEqual(data, b'\x78\x56\x34\x12')
 
     def test_write_object_to_file(self):
         obj = ('\u20ac', b'abc', 123, 45.6, 7+8j, 'long line '*1000)
         for v in range(marshal.version + 1):
-            _testcapi.pymarshal_write_object_to_file(obj, support.TESTFN, v)
-            with open(support.TESTFN, 'rb') as f:
+            _testcapi.pymarshal_write_object_to_file(obj, os_helper.TESTFN, v)
+            with open(os_helper.TESTFN, 'rb') as f:
                 data = f.read()
-            support.unlink(support.TESTFN)
+            os_helper.unlink(os_helper.TESTFN)
             self.assertEqual(marshal.loads(data), obj)
 
     def test_read_short_from_file(self):
-        with open(support.TESTFN, 'wb') as f:
+        with open(os_helper.TESTFN, 'wb') as f:
             f.write(b'\x34\x12xxxx')
-        r, p = _testcapi.pymarshal_read_short_from_file(support.TESTFN)
-        support.unlink(support.TESTFN)
+        r, p = _testcapi.pymarshal_read_short_from_file(os_helper.TESTFN)
+        os_helper.unlink(os_helper.TESTFN)
         self.assertEqual(r, 0x1234)
         self.assertEqual(p, 2)
 
-        with open(support.TESTFN, 'wb') as f:
+        with open(os_helper.TESTFN, 'wb') as f:
             f.write(b'\x12')
         with self.assertRaises(EOFError):
-            _testcapi.pymarshal_read_short_from_file(support.TESTFN)
-        support.unlink(support.TESTFN)
+            _testcapi.pymarshal_read_short_from_file(os_helper.TESTFN)
+        os_helper.unlink(os_helper.TESTFN)
 
     def test_read_long_from_file(self):
-        with open(support.TESTFN, 'wb') as f:
+        with open(os_helper.TESTFN, 'wb') as f:
             f.write(b'\x78\x56\x34\x12xxxx')
-        r, p = _testcapi.pymarshal_read_long_from_file(support.TESTFN)
-        support.unlink(support.TESTFN)
+        r, p = _testcapi.pymarshal_read_long_from_file(os_helper.TESTFN)
+        os_helper.unlink(os_helper.TESTFN)
         self.assertEqual(r, 0x12345678)
         self.assertEqual(p, 4)
 
-        with open(support.TESTFN, 'wb') as f:
+        with open(os_helper.TESTFN, 'wb') as f:
             f.write(b'\x56\x34\x12')
         with self.assertRaises(EOFError):
-            _testcapi.pymarshal_read_long_from_file(support.TESTFN)
-        support.unlink(support.TESTFN)
+            _testcapi.pymarshal_read_long_from_file(os_helper.TESTFN)
+        os_helper.unlink(os_helper.TESTFN)
 
     def test_read_last_object_from_file(self):
         obj = ('\u20ac', b'abc', 123, 45.6, 7+8j)
         for v in range(marshal.version + 1):
             data = marshal.dumps(obj, v)
-            with open(support.TESTFN, 'wb') as f:
+            with open(os_helper.TESTFN, 'wb') as f:
                 f.write(data + b'xxxx')
-            r, p = _testcapi.pymarshal_read_last_object_from_file(support.TESTFN)
-            support.unlink(support.TESTFN)
+            r, p = _testcapi.pymarshal_read_last_object_from_file(os_helper.TESTFN)
+            os_helper.unlink(os_helper.TESTFN)
             self.assertEqual(r, obj)
 
-            with open(support.TESTFN, 'wb') as f:
+            with open(os_helper.TESTFN, 'wb') as f:
                 f.write(data[:1])
             with self.assertRaises(EOFError):
-                _testcapi.pymarshal_read_last_object_from_file(support.TESTFN)
-            support.unlink(support.TESTFN)
+                _testcapi.pymarshal_read_last_object_from_file(os_helper.TESTFN)
+            os_helper.unlink(os_helper.TESTFN)
 
     def test_read_object_from_file(self):
         obj = ('\u20ac', b'abc', 123, 45.6, 7+8j)
         for v in range(marshal.version + 1):
             data = marshal.dumps(obj, v)
-            with open(support.TESTFN, 'wb') as f:
+            with open(os_helper.TESTFN, 'wb') as f:
                 f.write(data + b'xxxx')
-            r, p = _testcapi.pymarshal_read_object_from_file(support.TESTFN)
-            support.unlink(support.TESTFN)
+            r, p = _testcapi.pymarshal_read_object_from_file(os_helper.TESTFN)
+            os_helper.unlink(os_helper.TESTFN)
             self.assertEqual(r, obj)
             self.assertEqual(p, len(data))
 
-            with open(support.TESTFN, 'wb') as f:
+            with open(os_helper.TESTFN, 'wb') as f:
                 f.write(data[:1])
             with self.assertRaises(EOFError):
-                _testcapi.pymarshal_read_object_from_file(support.TESTFN)
-            support.unlink(support.TESTFN)
+                _testcapi.pymarshal_read_object_from_file(os_helper.TESTFN)
+            os_helper.unlink(os_helper.TESTFN)
 
 
 if __name__ == "__main__":