test: Add unit tests for urlDecode

Co-authored-by: Lőrinc <pap.lorinc@gmail.com>

Author: fjahr

src/Makefile.test.include

@@ -85,6 +85,7 @@ BITCOIN_TESTS =\
   test/checkqueue_tests.cpp \
   test/coins_tests.cpp \
   test/coinstatsindex_tests.cpp \
+  test/common_url_tests.cpp \
   test/compilerbug_tests.cpp \
   test/compress_tests.cpp \
   test/crypto_tests.cpp \

src/test/common_url_tests.cpp

@@ -0,0 +1,70 @@
+// Copyright (c) 2024-present The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or https://opensource.org/license/mit/.
+
+#include <common/url.h>
+
+#include <string>
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_AUTO_TEST_SUITE(common_url_tests)
+
+// These test vectors were ported from test/regress.c in the libevent library
+// which used to be a dependency of the urlDecode function.
+
+BOOST_AUTO_TEST_CASE(encode_decode_test) {
+    BOOST_CHECK_EQUAL(urlDecode("Hello"), "Hello");
+    BOOST_CHECK_EQUAL(urlDecode("99"), "99");
+    BOOST_CHECK_EQUAL(urlDecode(""), "");
+    BOOST_CHECK_EQUAL(urlDecode("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ123456789-.~_"),
+                      "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ123456789-.~_");
+    BOOST_CHECK_EQUAL(urlDecode("%20"), " ");
+    BOOST_CHECK_EQUAL(urlDecode("%FF%F0%E0"), "\xff\xf0\xe0");
+    BOOST_CHECK_EQUAL(urlDecode("%01%19"), "\x01\x19");
+    BOOST_CHECK_EQUAL(urlDecode("http%3A%2F%2Fwww.ietf.org%2Frfc%2Frfc3986.txt"),
+                      "http://www.ietf.org/rfc/rfc3986.txt");
+    BOOST_CHECK_EQUAL(urlDecode("1%2B2%3D3"), "1+2=3");
+}
+
+BOOST_AUTO_TEST_CASE(decode_malformed_test) {
+    BOOST_CHECK_EQUAL(urlDecode("%%xhello th+ere \xff"), "%%xhello th+ere \xff");
+
+    BOOST_CHECK_EQUAL(urlDecode("%"), "%");
+    BOOST_CHECK_EQUAL(urlDecode("%%"), "%%");
+    BOOST_CHECK_EQUAL(urlDecode("%%%"), "%%%");
+    BOOST_CHECK_EQUAL(urlDecode("%%%%"), "%%%%");
+
+    BOOST_CHECK_EQUAL(urlDecode("+"), "+");
+    BOOST_CHECK_EQUAL(urlDecode("++"), "++");
+
+    BOOST_CHECK_EQUAL(urlDecode("?"), "?");
+    BOOST_CHECK_EQUAL(urlDecode("??"), "??");
+
+    BOOST_CHECK_EQUAL(urlDecode("%G1"), "%G1");
+    BOOST_CHECK_EQUAL(urlDecode("%2"), "%2");
+    BOOST_CHECK_EQUAL(urlDecode("%ZX"), "%ZX");
+
+    BOOST_CHECK_EQUAL(urlDecode("valid%20string%G1"), "valid string%G1");
+    BOOST_CHECK_EQUAL(urlDecode("%20invalid%ZX"), " invalid%ZX");
+    BOOST_CHECK_EQUAL(urlDecode("%20%G1%ZX"), " %G1%ZX");
+
+    BOOST_CHECK_EQUAL(urlDecode("%1 "), "%1 ");
+    BOOST_CHECK_EQUAL(urlDecode("% 9"), "% 9");
+    BOOST_CHECK_EQUAL(urlDecode(" %Z "), " %Z ");
+    BOOST_CHECK_EQUAL(urlDecode(" % X"), " % X");
+
+    BOOST_CHECK_EQUAL(urlDecode("%-1"), "%-1");
+    BOOST_CHECK_EQUAL(urlDecode("%1-"), "%1-");
+}
+
+BOOST_AUTO_TEST_CASE(decode_lowercase_hex_test) {
+    BOOST_CHECK_EQUAL(urlDecode("%f0%a0%b0"), "\xf0\xa0\xb0");
+}
+
+BOOST_AUTO_TEST_CASE(decode_internal_nulls_test) {
+    BOOST_CHECK_EQUAL(urlDecode("%00%00x%00%00"), "");
+    BOOST_CHECK_EQUAL(urlDecode("abc%00%00"), "abc");
+}
+
+BOOST_AUTO_TEST_SUITE_END()