diff --git a/arrays-strings/unique_chars.ipynb b/arrays-strings/unique_chars.ipynb
index ad89b7c..2af80af 100644
--- a/arrays-strings/unique_chars.ipynb
+++ b/arrays-strings/unique_chars.ipynb
@@ -90,12 +90,19 @@
    },
    "outputs": [],
    "source": [
-    "def test():\n",
-    "    print(unique_chars(''))\n",
-    "    print(unique_chars('foo'))\n",
-    "    print(unique_chars('bar'))\n",
+    "from nose.tools import assert_equal\n",
     "\n",
-    "test()"
+    "class Test(object):\n",
+    "  def test_unique_chars(self):\n",
+    "        assert_equal(unique_chars(''), True)\n",
+    "        assert_equal(unique_chars('foo'), False)\n",
+    "        assert_equal(unique_chars('bar'), True)    \n",
+    "\n",
+    "def run_tests():\n",
+    "    test = Test()\n",
+    "    test.test_unique_chars()\n",
+    "\n",
+    "run_tests()"
    ]
   },
   {
@@ -146,7 +153,7 @@
     "            chars_set.add(char)\n",
     "    return True\n",
     "\n",
-    "test()"
+    "run_tests()"
    ]
   },
   {
@@ -189,7 +196,7 @@
     "            return False\n",
     "    return True\n",
     "\n",
-    "test()"
+    "run_tests()"
    ]
   }
  ],