Issue #29416: Prevent infinite loop in pathlib.Path.mkdir

1 files changed, 54 insertions, 0 deletions

diff --git a/Lib/test/test_symbol.py b/Lib/test/test_symbol.py
new file mode 100644
index 0000000000..c1306f5432
--- /dev/null
+++ b/Lib/test/test_symbol.py
@@ -0,0 +1,54 @@
+import unittest
+from test import support
+import os
+import sys
+import subprocess
+
+
+SYMBOL_FILE              = support.findfile('symbol.py')
+GRAMMAR_FILE             = os.path.join(os.path.dirname(__file__),
+                                        '..', '..', 'Include', 'graminit.h')
+TEST_PY_FILE             = 'symbol_test.py'
+
+
+class TestSymbolGeneration(unittest.TestCase):
+
+    def _copy_file_without_generated_symbols(self, source_file, dest_file):
+        with open(source_file) as fp:
+            lines = fp.readlines()
+        with open(dest_file, 'w') as fp:
+            fp.writelines(lines[:lines.index("#--start constants--\n") + 1])
+            fp.writelines(lines[lines.index("#--end constants--\n"):])
+
+    def _generate_symbols(self, grammar_file, target_symbol_py_file):
+        proc = subprocess.Popen([sys.executable,
+                                 SYMBOL_FILE,
+                                 grammar_file,
+                                 target_symbol_py_file], stderr=subprocess.PIPE)
+        stderr = proc.communicate()[1]
+        return proc.returncode, stderr
+
+    def compare_files(self, file1, file2):
+        with open(file1) as fp:
+            lines1 = fp.readlines()
+        with open(file2) as fp:
+            lines2 = fp.readlines()
+        self.assertEqual(lines1, lines2)
+
+    @unittest.skipIf(not os.path.exists(GRAMMAR_FILE),
+                     'test only works from source build directory')
+    def test_real_grammar_and_symbol_file(self):
+        output = support.TESTFN
+        self.addCleanup(support.unlink, output)
+
+        self._copy_file_without_generated_symbols(SYMBOL_FILE, output)
+
+        exitcode, stderr = self._generate_symbols(GRAMMAR_FILE, output)
+        self.assertEqual(b'', stderr)
+        self.assertEqual(0, exitcode)
+
+        self.compare_files(SYMBOL_FILE, output)
+
+
+if __name__ == "__main__":
+    unittest.main()