test: Add additional test cases

Author: corona10

builtin/tests/builtin.py

@@ -22,6 +22,9 @@
 doc="ascii"
 assert ascii('hello world') == "'hello world'"
 assert ascii('안녕 세상') == "'\\uc548\\ub155 \\uc138\\uc0c1'"
+assert ascii('\\') == "'\\\\'"
+assert ascii('\t\r\n') == "'\\t\\r\\n'"
+assert ascii("\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F") == "'\\x00\\x01\\x02\\x03\\x04\\x05\\x06\\x07\\x08\\t\\n\\x0b\\x0c\\r\\x0e\\x0f\\x10\\x11\\x12\\x13\\x14\\x15\\x16\\x17\\x18\\x19\\x1a\\x1b\\x1c\\x1d\\x1e\\x1f'"
 
 doc="chr"
 assert chr(65) == "A"