1 files changed, 67 insertions, 0 deletions
diff --git a/Lib/test/test_capi/test_file.py b/Lib/test/test_capi/test_file.py
new file mode 100644
index 0000000..8a08a0a
--- /dev/null
+++ b/Lib/test/test_capi/test_file.py
@@ -0,0 +1,67 @@
+import os
+import unittest
+from test import support
+from test.support import import_helper, os_helper
+
+_testcapi = import_helper.import_module('_testcapi')
+
+
+class CAPIFileTest(unittest.TestCase):
+    def test_py_fopen(self):
+        # Test Py_fopen() and Py_fclose()
+
+        with open(__file__, "rb") as fp:
+            source = fp.read()
+
+        for filename in (__file__, os.fsencode(__file__)):
+            with self.subTest(filename=filename):
+                data = _testcapi.py_fopen(filename, "rb")
+                self.assertEqual(data, source[:256])
+
+                data = _testcapi.py_fopen(os_helper.FakePath(filename), "rb")
+                self.assertEqual(data, source[:256])
+
+        filenames = [
+            os_helper.TESTFN,
+            os.fsencode(os_helper.TESTFN),
+        ]
+        # TESTFN_UNDECODABLE cannot be used to create a file on macOS/WASI.
+        if os_helper.TESTFN_UNENCODABLE is not None:
+            filenames.append(os_helper.TESTFN_UNENCODABLE)
+        for filename in filenames:
+            with self.subTest(filename=filename):
+                try:
+                    with open(filename, "wb") as fp:
+                        fp.write(source)
+
+                    data = _testcapi.py_fopen(filename, "rb")
+                    self.assertEqual(data, source[:256])
+                finally:
+                    os_helper.unlink(filename)
+
+        # embedded null character/byte in the filename
+        with self.assertRaises(ValueError):
+            _testcapi.py_fopen("a\x00b", "rb")
+        with self.assertRaises(ValueError):
+            _testcapi.py_fopen(b"a\x00b", "rb")
+
+        # non-ASCII mode failing with "Invalid argument"
+        with self.assertRaises(OSError):
+            _testcapi.py_fopen(__file__, "\xe9")
+
+        # invalid filename type
+        for invalid_type in (123, object()):
+            with self.subTest(filename=invalid_type):
+                with self.assertRaises(TypeError):
+                    _testcapi.py_fopen(invalid_type, "rb")
+
+        if support.MS_WINDOWS:
+            with self.assertRaises(OSError):
+                # On Windows, the file mode is limited to 10 characters
+                _testcapi.py_fopen(__file__, "rt+, ccs=UTF-8")
+
+        # CRASHES py_fopen(__file__, None)
+
+
+if __name__ == "__main__":
+    unittest.main()