Add tests

Author: encukou

Lib/test/test_capi/test_long.py

@@ -0,0 +1,39 @@
+import unittest
+import sys
+
+from test.support import import_helper
+
+# Skip this test if the _testcapi module isn't available.
+_testcapi = import_helper.import_module('_testcapi')
+
+
+class LongTests(unittest.TestCase):
+
+    def test_compact(self):
+        for n in {
+            # Edge cases
+            *(2**n for n in range(66)),
+            *(-2**n for n in range(66)),
+            *(2**n - 1 for n in range(66)),
+            *(-2**n + 1 for n in range(66)),
+            # Essentially random
+            *(37**n for n in range(14)),
+            *(-37**n for n in range(14)),
+        }:
+            with self.subTest(n=n):
+                is_compact, value = _testcapi.call_long_compact_api(n)
+                if is_compact:
+                    self.assertEqual(n, value)
+
+    def test_compact_known(self):
+        # Sanity-check some implementation details (we don't guarantee
+        # that these are/aren't compact)
+        self.assertEqual(_testcapi.call_long_compact_api(-1), (True, 0))
+        self.assertEqual(_testcapi.call_long_compact_api(0), (True, 0))
+        self.assertEqual(_testcapi.call_long_compact_api(256), (True, 256))
+        self.assertEqual(_testcapi.call_long_compact_api(sys.maxsize),
+                         (False, -1))
+
+
+if __name__ == "__main__":
+    unittest.main()

Modules/_testcapi/long.c

@@ -534,6 +534,18 @@ test_long_numbits(PyObject *self, PyObject *Py_UNUSED(ignored))
     Py_RETURN_NONE;
 }
 
+static PyObject *
+check_long_compact_api(PyObject *self, PyObject *arg)
+{
+    assert(PyLong_Check(arg));
+    int is_compact = PyUnstable_Long_IsCompact((PyLongObject*)arg);
+    Py_ssize_t value = -1;
+    if (is_compact) {
+        value = PyUnstable_Long_CompactValue((PyLongObject*)arg);
+    }
+    return Py_BuildValue("in", is_compact, value);
+}
+
 static PyMethodDef test_methods[] = {
     {"test_long_and_overflow",  test_long_and_overflow,          METH_NOARGS},
     {"test_long_api",           test_long_api,                   METH_NOARGS},
@@ -543,6 +555,7 @@ static PyMethodDef test_methods[] = {
     {"test_long_long_and_overflow",test_long_long_and_overflow,  METH_NOARGS},
     {"test_long_numbits",       test_long_numbits,               METH_NOARGS},
     {"test_longlong_api",       test_longlong_api,               METH_NOARGS},
+    {"call_long_compact_api",   check_long_compact_api,          METH_O},
     {NULL},
 };