Merge #21488: test: add ParseUInt16() unit test and fuzz coverage

3d086f42ab test: add ParseUInt16() test coverage (Jon Atack)

Pull request description:

  `ParseUInt16()` was just added in #21328.

ACKs for top commit:
  practicalswift:
    cr ACK 3d086f42ab58f0f5984101d5285d5a707e3dc8e7: patch looks correct & more coverage is better than less coverage

Tree-SHA512: bf7f96deb7c1531419565907f0ea8a8e32b368d4b823a3e80928b2c118edbf643ea06e357b4b5504a89f855caeed289daa9f823c740231ed6ad1b8ed00285ce8

src/test/fuzz/parse_numbers.cpp

@@ -21,6 +21,9 @@ FUZZ_TARGET(parse_numbers)
     uint8_t u8;
     (void)ParseUInt8(random_string, &u8);
 
+    uint16_t u16;
+    (void)ParseUInt16(random_string, &u16);
+
     int32_t i32;
     (void)ParseInt32(random_string, &i32);
     (void)atoi(random_string);

src/test/util_tests.cpp

@@ -1523,6 +1523,42 @@ BOOST_AUTO_TEST_CASE(test_ParseUInt8)
     BOOST_CHECK(!ParseUInt8("256", nullptr));
 }
 
+BOOST_AUTO_TEST_CASE(test_ParseUInt16)
+{
+    uint16_t n;
+    // Valid values
+    BOOST_CHECK(ParseUInt16("1234", nullptr));
+    BOOST_CHECK(ParseUInt16("0", &n) && n == 0);
+    BOOST_CHECK(ParseUInt16("1234", &n) && n == 1234);
+    BOOST_CHECK(ParseUInt16("01234", &n) && n == 1234); // no octal
+    BOOST_CHECK(ParseUInt16("65535", &n) && n == static_cast<uint16_t>(65535));
+    BOOST_CHECK(ParseUInt16("+65535", &n) && n == 65535);
+    BOOST_CHECK(ParseUInt16("00000000000000000012", &n) && n == 12);
+    BOOST_CHECK(ParseUInt16("00000000000000000000", &n) && n == 0);
+    // Invalid values
+    BOOST_CHECK(!ParseUInt16("-00000000000000000000", &n));
+    BOOST_CHECK(!ParseUInt16("", &n));
+    BOOST_CHECK(!ParseUInt16(" 1", &n)); // no padding inside
+    BOOST_CHECK(!ParseUInt16(" -1", &n));
+    BOOST_CHECK(!ParseUInt16("++1", &n));
+    BOOST_CHECK(!ParseUInt16("+-1", &n));
+    BOOST_CHECK(!ParseUInt16("-+1", &n));
+    BOOST_CHECK(!ParseUInt16("--1", &n));
+    BOOST_CHECK(!ParseUInt16("-1", &n));
+    BOOST_CHECK(!ParseUInt16("1 ", &n));
+    BOOST_CHECK(!ParseUInt16("1a", &n));
+    BOOST_CHECK(!ParseUInt16("aap", &n));
+    BOOST_CHECK(!ParseUInt16("0x1", &n)); // no hex
+    BOOST_CHECK(!ParseUInt16("0x1", &n)); // no hex
+    BOOST_CHECK(!ParseUInt16(STRING_WITH_EMBEDDED_NULL_CHAR, &n));
+    // Overflow and underflow
+    BOOST_CHECK(!ParseUInt16("-65535", &n));
+    BOOST_CHECK(!ParseUInt16("65536", &n));
+    BOOST_CHECK(!ParseUInt16("-123", &n));
+    BOOST_CHECK(!ParseUInt16("-123", nullptr));
+    BOOST_CHECK(!ParseUInt16("65536", nullptr));
+}
+
 BOOST_AUTO_TEST_CASE(test_ParseUInt32)
 {
     uint32_t n;