bpo-40275: Use new test.support helper submodules in tests (GH-21448)

diff --git a/Lib/test/test_doctest.py b/Lib/test/test_doctest.py
index 8d9f872..bff20f9 100644
--- a/Lib/test/test_doctest.py
+++ b/Lib/test/test_doctest.py
@@ -3,6 +3,8 @@
 """
 
 from test import support
+from test.support import import_helper
+from test.support import os_helper
 import doctest
 import functools
 import os
@@ -441,7 +443,7 @@
     >>> tests = finder.find(sample_func)
 
     >>> print(tests)  # doctest: +ELLIPSIS
-    [<DocTest sample_func from ...:25 (1 example)>]
+    [<DocTest sample_func from ...:27 (1 example)>]
 
 The exact name depends on how test_doctest was invoked, so allow for
 leading path components.
@@ -705,7 +707,7 @@
             try:
                 mod = importlib.import_module(pkg_name)
             finally:
-                support.forget(pkg_name)
+                import_helper.forget(pkg_name)
                 sys.path.pop()
 
             include_empty_finder = doctest.DocTestFinder(exclude_empty=False)
@@ -2758,7 +2760,7 @@
     >>> dn = tempfile.mkdtemp()
     >>> pkg = os.path.join(dn, "doctest_testpkg")
     >>> os.mkdir(pkg)
-    >>> support.create_empty_file(os.path.join(pkg, "__init__.py"))
+    >>> os_helper.create_empty_file(os.path.join(pkg, "__init__.py"))
     >>> fn = os.path.join(pkg, "doctest_testfile.txt")
     >>> with open(fn, 'wb') as f:
     ...     f.write(
@@ -2840,7 +2842,8 @@
 simple tests and no errors.  We'll run both the unadorned doctest command, and
 the verbose version, and then check the output:
 
-    >>> from test.support import script_helper, temp_dir
+    >>> from test.support import script_helper
+    >>> from test.support.os_helper import temp_dir
     >>> with temp_dir() as tmpdir:
     ...     fn = os.path.join(tmpdir, 'myfile.doc')
     ...     with open(fn, 'w') as f:
@@ -2891,7 +2894,8 @@
 file ends in '.py', its handling of python module files (as opposed to straight
 text files).
 
-    >>> from test.support import script_helper, temp_dir
+    >>> from test.support import script_helper
+    >>> from test.support.os_helper import temp_dir
     >>> with temp_dir() as tmpdir:
     ...     fn = os.path.join(tmpdir, 'myfile.doc')
     ...     with open(fn, 'w') as f:
@@ -3109,7 +3113,7 @@
 
 
 def test_coverage(coverdir):
-    trace = support.import_module('trace')
+    trace = import_helper.import_module('trace')
     tracer = trace.Trace(ignoredirs=[sys.base_prefix, sys.base_exec_prefix,],
                          trace=0, count=1)
     tracer.run('test_main()')