assert that the regex given to assertRegex is non-empty.
diff --git a/Lib/unittest/case.py b/Lib/unittest/case.py
index 0ad7857..6752e7a 100644
--- a/Lib/unittest/case.py
+++ b/Lib/unittest/case.py
@@ -1121,6 +1121,7 @@
def assertRegex(self, text, expected_regex, msg=None):
"""Fail the test unless the text matches the regular expression."""
if isinstance(expected_regex, (str, bytes)):
+ assert expected_regex, "expected_regex must not be empty."
expected_regex = re.compile(expected_regex)
if not expected_regex.search(text):
msg = msg or "Regex didn't match"