Fix mis-caching of arguments containing colons

The usage of quote() is inspired by Django's own `make_template_fragment_key`.

Fixes #32

src/cache_memoize/__init__.py

@@ -1,9 +1,11 @@
 from functools import wraps
 
 import hashlib
+from urllib.parse import quote
+
 from django.core.cache import caches, DEFAULT_CACHE_ALIAS
 
-from django.utils.encoding import force_text, force_bytes
+from django.utils.encoding import force_bytes
 
 MARKER = object()
 
@@ -91,8 +93,8 @@ def noop(*args):
     def decorator(func):
         def _default_make_cache_key(*args, **kwargs):
             cache_key = ":".join(
-                [force_text(x) for x in args_rewrite(*args)]
-                + [force_text("{}={}".format(k, v)) for k, v in kwargs.items()]
+                [quote(str(x)) for x in args_rewrite(*args)]
+                + [quote("{}={}".format(k, v)) for k, v in kwargs.items()]
             )
             return hashlib.md5(
                 force_bytes("cache_memoize" + (prefix or func.__name__) + cache_key)

tests/test_cache_memoize.py

@@ -2,6 +2,7 @@
 import random
 from threading import Thread, Lock
 
+import pytest
 from django.core.cache import cache
 
 from cache_memoize import cache_memoize
@@ -72,6 +73,27 @@ def returnnothing(a, b, k="bla"):
     assert len(calls_made) == 1
 
 
+@pytest.mark.parametrize(
+    "bits", [("a", "b", "c"), ("ä", "á", "ö"), ("ë".encode(), b"\02", b"i")]
+)
+def test_colons(bits):
+    calls_made = []
+
+    @cache_memoize(10)
+    def fun(a, b, k="bla"):
+        calls_made.append((a, b, k))
+        return (a, b, k)
+
+    sep = ":"
+    if isinstance(bits[0], bytes):
+        sep = sep.encode()
+    a1, a2 = (sep.join(bits[:2]), bits[2])
+    b1, b2 = (bits[0], sep.join(bits[1:]))
+    fun(a1, a2)
+    fun(b1, b2)
+    assert len(calls_made) == 2
+
+
 def test_cache_memoize_hit_miss_callables():
 
     hits = []