Fixed regression in UTF16 decoding (fixes #1173)

extras/tests/JsonDeserializer/string.cpp

@@ -21,6 +21,9 @@ TEST_CASE("Valid JSON strings value") {
       {"'\\u00E4'", "\xc3\xa4"},                 // ä
       {"'\\u3042'", "\xe3\x81\x82"},             // あ
       {"'\\ud83d\\udda4'", "\xf0\x9f\x96\xa4"},  // 🖤
+      {"'\\uF053'", "\xef\x81\x93"},             // issue #1173
+      {"'\\uF015'", "\xef\x80\x95"},             // issue #1173
+      {"'\\uF054'", "\xef\x81\x94"},             // issue #1173
   };
   const size_t testCount = sizeof(testCases) / sizeof(testCases[0]);
 

extras/tests/Misc/CMakeLists.txt

@@ -11,6 +11,7 @@ add_executable(MiscTests
 	TypeTraits.cpp
 	unsigned_char.cpp
 	Utf8.cpp
+	Utf16.cpp
 	version.cpp
 )
 

extras/tests/Misc/Utf16.cpp

@@ -0,0 +1,68 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2020
+// MIT License
+
+#include <ArduinoJson/Json/Utf16.hpp>
+#include <catch.hpp>
+
+using namespace ARDUINOJSON_NAMESPACE;
+
+static void testUtf16Codepoint(uint16_t codeunit, uint32_t expectedCodepoint) {
+  Utf16::Codepoint cp;
+  REQUIRE(cp.append(codeunit) == true);
+  REQUIRE(cp.value() == expectedCodepoint);
+}
+
+static void testUtf16Codepoint(uint16_t codeunit1, uint16_t codeunit2,
+                               uint32_t expectedCodepoint) {
+  Utf16::Codepoint cp;
+  REQUIRE(cp.append(codeunit1) == false);
+  REQUIRE(cp.append(codeunit2) == true);
+  REQUIRE(cp.value() == expectedCodepoint);
+}
+
+TEST_CASE("Utf16::Codepoint()") {
+  SECTION("U+0000") {
+    testUtf16Codepoint(0x0000, 0x000000);
+  }
+
+  SECTION("U+0001") {
+    testUtf16Codepoint(0x0001, 0x000001);
+  }
+
+  SECTION("U+D7FF") {
+    testUtf16Codepoint(0xD7FF, 0x00D7FF);
+  }
+
+  SECTION("U+E000") {
+    testUtf16Codepoint(0xE000, 0x00E000);
+  }
+
+  SECTION("U+FFFF") {
+    testUtf16Codepoint(0xFFFF, 0x00FFFF);
+  }
+
+  SECTION("U+010000") {
+    testUtf16Codepoint(0xD800, 0xDC00, 0x010000);
+  }
+
+  SECTION("U+010001") {
+    testUtf16Codepoint(0xD800, 0xDC01, 0x010001);
+  }
+
+  SECTION("U+0103FF") {
+    testUtf16Codepoint(0xD800, 0xDFFF, 0x0103FF);
+  }
+
+  SECTION("U+010400") {
+    testUtf16Codepoint(0xD801, 0xDC00, 0x010400);
+  }
+
+  SECTION("U+010400") {
+    testUtf16Codepoint(0xDBFF, 0xDC00, 0x10FC00);
+  }
+
+  SECTION("U+10FFFF") {
+    testUtf16Codepoint(0xDBFF, 0xDFFF, 0x10FFFF);
+  }
+}