1 files changed, 14 insertions, 0 deletions
diff --git a/Lib/test/test_complex.py b/Lib/test/test_complex.py
index 403ee3bc58..c249ca724b 100644
--- a/Lib/test/test_complex.py
+++ b/Lib/test/test_complex.py
@@ -1,5 +1,7 @@
 import unittest
 from test import support
+from test.test_grammar import (VALID_UNDERSCORE_LITERALS,
+                               INVALID_UNDERSCORE_LITERALS)
 
 from random import random
 from math import atan2, isnan, copysign
@@ -385,6 +387,18 @@ class ComplexTest(unittest.TestCase):
         self.assertAlmostEqual(complex(complex1(1j)), 2j)
         self.assertRaises(TypeError, complex, complex2(1j))
 
+    def test_underscores(self):
+        # check underscores
+        for lit in VALID_UNDERSCORE_LITERALS:
+            if not any(ch in lit for ch in 'xXoObB'):
+                self.assertEqual(complex(lit), eval(lit))
+                self.assertEqual(complex(lit), complex(lit.replace('_', '')))
+        for lit in INVALID_UNDERSCORE_LITERALS:
+            if lit in ('0_7', '09_99'):  # octals are not recognized here
+                continue
+            if not any(ch in lit for ch in 'xXoObB'):
+                self.assertRaises(ValueError, complex, lit)
+
     def test_hash(self):
         for x in range(-30, 30):
             self.assertEqual(hash(x), hash(complex(x, 0)))