Remove unused function.

core/util/string_helpers.py

@@ -1,21 +1,10 @@
 # Helper functions and objects regarding strings -- especially stuff
 # that lets us negotiate the distinction between Unicode and
 # bytestrings.
-import binascii
-import os
 import secrets
 import string
 
 
-def random_string(size: int) -> str:
-    """Generate a random string of binary, encoded as hex digits.
-
-    :param: Size of binary string in bytes.
-    :return: A Unicode string.
-    """
-    return binascii.hexlify(os.urandom(size)).decode("utf8")
-
-
 def random_key(size: int) -> str:
     """Generate a random string suitable for use as a key.
 

tests/core/util/test_string_helpers.py

@@ -1,34 +1,8 @@
 # Test the helper objects in util.string.
 
-import re
 import string
 
-from core.util.string_helpers import random_key, random_string
-
-
-def test_random_string():
-    m = random_string
-    assert "" == m(0)
-
-    # The strings are random.
-    res1 = m(8)
-    res2 = m(8)
-    assert res1 != res2
-
-    # We can't test exact values, because the randomness comes
-    # from /dev/urandom, but we can test some of their properties:
-    for size in range(1, 16):
-        x = m(size)
-
-        # The strings are Unicode strings, not bytestrings
-        assert isinstance(x, str)
-
-        # The strings are entirely composed of lowercase hex digits.
-        assert None == re.compile("[^a-f0-9]").search(x)
-
-        # Each byte is represented as two digits, so the length of the
-        # string is twice the length passed in to the function.
-        assert size * 2 == len(x)
+from core.util.string_helpers import random_key
 
 
 def test_random_key():