Removed implicit conversion in comparison operators (issue #998)

test/Misc/CMakeLists.txt

@@ -6,6 +6,7 @@ add_executable(MiscTests
 	conflicts.cpp
 	FloatParts.cpp
 	StreamReader.cpp
+	StringAdapters.cpp
 	StringWriter.cpp
 	TypeTraits.cpp
 	unsigned_char.cpp

test/Misc/StringAdapters.cpp

@@ -0,0 +1,45 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2019
+// MIT License
+
+#include <ArduinoJson.h>
+#include <catch.hpp>
+
+using namespace ARDUINOJSON_NAMESPACE;
+
+TEST_CASE("ConstRamStringAdapter") {
+  SECTION("null") {
+    ConstRamStringAdapter adapter(NULL);
+
+    REQUIRE(adapter.compare("bravo") < 0);
+    REQUIRE(adapter.compare(NULL) == 0);
+
+    REQUIRE(adapter.equals(NULL));
+    REQUIRE_FALSE(adapter.equals("charlie"));
+  }
+
+  SECTION("non-null") {
+    ConstRamStringAdapter adapter("bravo");
+
+    REQUIRE(adapter.compare(NULL) > 0);
+    REQUIRE(adapter.compare("alpha") > 0);
+    REQUIRE(adapter.compare("bravo") == 0);
+    REQUIRE(adapter.compare("charlie") < 0);
+
+    REQUIRE(adapter.equals("bravo"));
+    REQUIRE_FALSE(adapter.equals("charlie"));
+  }
+}
+
+TEST_CASE("StlString") {
+  std::string str("bravo");
+  StlStringAdapter adapter(str);
+
+  REQUIRE(adapter.compare(NULL) > 0);
+  REQUIRE(adapter.compare("alpha") > 0);
+  REQUIRE(adapter.compare("bravo") == 0);
+  REQUIRE(adapter.compare("charlie") < 0);
+
+  REQUIRE(adapter.equals("bravo"));
+  REQUIRE_FALSE(adapter.equals("charlie"));
+}