Add regression tests for unsigned constants

Large, unsigned, constants result in an Overflow error.

I discovered this while running CBI on a new code base that tries to check
the value of ULONG_MAX.

Signed-off-by: John Pennycook <john.pennycook@intel.com>

Author: Pennycook

tests/literals/test_literals.py

@@ -5,6 +5,8 @@
 import unittest
 from pathlib import Path
 
+import numpy as np
+
 from codebasin import CodeBase, finder, preprocessor
 
 
@@ -60,6 +62,11 @@ def test_strings(self):
         )
         self.assertEqual(tokens[0].token, expected.token)
 
+    def test_long_constants(self):
+        tokens = preprocessor.Lexer("0xFFFFFFFFFFFFFFFFULL").tokenize()
+        term = preprocessor.ExpressionEvaluator(tokens).term()
+        self.assertEqual(term, np.uint64(int("0xFFFFFFFFFFFFFFFF", 16)))
+
 
 if __name__ == "__main__":
     unittest.main()