bpo-30695: Add set_nomemory(start, stop) to _testcapi (GH-2406)

Lib/test/test_capi.py

@@ -15,7 +15,7 @@ import time
 import unittest
 from test import support
 from test.support import MISSING_C_DOCSTRINGS
-from test.support.script_helper import assert_python_failure
+from test.support.script_helper import assert_python_failure, assert_python_ok
 try:
     import _posixsubprocess
 except ImportError:
@@ -243,6 +243,38 @@ class CAPITest(unittest.TestCase):
     def test_buildvalue_N(self):
         _testcapi.test_buildvalue_N()
 
+    def test_set_nomemory(self):
+        code = """if 1:
+            import _testcapi
+
+            class C(): pass
+
+            # The first loop tests both functions and that remove_mem_hooks()
+            # can be called twice in a row. The second loop checks a call to
+            # set_nomemory() after a call to remove_mem_hooks(). The third
+            # loop checks the start and stop arguments of set_nomemory().
+            for outer_cnt in range(1, 4):
+                start = 10 * outer_cnt
+                for j in range(100):
+                    if j == 0:
+                        if outer_cnt != 3:
+                            _testcapi.set_nomemory(start)
+                        else:
+                            _testcapi.set_nomemory(start, start + 1)
+                    try:
+                        C()
+                    except MemoryError as e:
+                        if outer_cnt != 3:
+                            _testcapi.remove_mem_hooks()
+                        print('MemoryError', outer_cnt, j)
+                        _testcapi.remove_mem_hooks()
+                        break
+        """
+        rc, out, err = assert_python_ok('-c', code)
+        self.assertIn(b'MemoryError 1 10', out)
+        self.assertIn(b'MemoryError 2 20', out)
+        self.assertIn(b'MemoryError 3 30', out)
+
 
 @unittest.skipUnless(threading, 'Threading required for this test.')
 class TestPendingCalls(unittest.TestCase):