fix unicode string literal escape

test/util/stringutil.cpp

@@ -1,4 +1,5 @@
 #include "util/stringutil.hpp"
+#include "coders/BasicParser.hpp"
 
 #include <gtest/gtest.h>
 
@@ -16,6 +17,25 @@ TEST(stringutil, utf8) {
     EXPECT_EQ(str, str2);
 }
 
+static std::wstring gen_random_unicode_wstring(int n) {
+    std::wstring str;
+    str.resize(n);
+    for (int i = 0; i < n; i++) {
+        // wstring is 16 bit in some systems
+        str[i] = rand() & 0xFFFF;
+    }
+    return str;
+}
+
+TEST(stringutil, utf8_random) {
+    srand(5436324);
+
+    auto str = gen_random_unicode_wstring(10'000);
+    auto utf8str = util::wstr2str_utf8(str);
+    auto back = util::str2wstr_utf8(utf8str);
+    EXPECT_EQ(str, back);
+}
+
 TEST(stringutil, base64) {
     srand(2019);
     for (size_t size = 0; size < 30; size++) {
@@ -47,3 +67,37 @@ TEST(stringutil, base64_urlsafe) {
         }
     }
 }
+
+class StringParser : BasicParser<char> {
+public:
+    StringParser(std::string_view source) : BasicParser("<string>", source) {}
+
+    std::string parse() {
+        ++pos;
+        return parseString(source[0], true);
+    }
+};
+
+TEST(stringutil, escape_cases) {
+    auto escaped = util::escape("тест5", true);
+    auto expected = "\"\\u0442\\u0435\\u0441\\u04425\"";
+    ASSERT_EQ(expected, escaped);
+
+    srand(345873458);
+    for (int i = 0; i < 36; i++) {
+        rand();
+    }
+
+    auto str = gen_random_unicode_wstring(40);
+    auto utf8str = util::wstr2str_utf8(str);
+    escaped = util::escape(utf8str, true);
+
+    StringParser parser(escaped);
+    auto restored = parser.parse();
+    for (int i = 0; i < utf8str.length(); i++) {
+        if (utf8str[i] != restored[i]) {
+            std::cout << i << ": " << (int)utf8str[i] << " " << (int)restored[i] << std::endl;
+        }
+    }
+    EXPECT_EQ(utf8str, restored);
+}