Added JsonVariant::operator| to return a default value

test/JsonVariant/CMakeLists.txt

@@ -7,6 +7,7 @@ add_executable(JsonVariantTests
 	compare.cpp
 	copy.cpp
 	is.cpp
+	or.cpp
 	printTo.cpp
 	set_get.cpp
 	subscript.cpp

test/JsonVariant/or.cpp

@@ -0,0 +1,77 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2017
+// MIT License
+
+#include <ArduinoJson.h>
+#include <catch.hpp>
+
+static const JsonVariant undefined;
+static const JsonVariant null = static_cast<const char*>(0);
+
+TEST_CASE("JsonVariant::operator|()") {
+  SECTION("undefined | const char*") {
+    std::string result = undefined | "default";
+    REQUIRE(result == "default");
+  }
+
+  SECTION("undefined | int") {
+    int result = undefined | 42;
+    REQUIRE(result == 42);
+  }
+
+  SECTION("undefined | bool") {
+    bool result = undefined | true;
+    REQUIRE(result == true);
+  }
+
+  SECTION("null | const char*") {
+    std::string result = null | "default";
+    REQUIRE(result == "default");
+  }
+
+  SECTION("null | int") {
+    int result = null | 42;
+    REQUIRE(result == 42);
+  }
+
+  SECTION("null | bool") {
+    bool result = null | true;
+    REQUIRE(result == true);
+  }
+
+  SECTION("int | const char*") {
+    JsonVariant variant = 42;
+    std::string result = variant | "default";
+    REQUIRE(result == "default");
+  }
+
+  SECTION("int | int") {
+    JsonVariant variant = 0;
+    int result = variant | 666;
+    REQUIRE(result == 0);
+  }
+
+  SECTION("bool | bool") {
+    JsonVariant variant = false;
+    bool result = variant | true;
+    REQUIRE(result == false);
+  }
+
+  SECTION("int | bool") {
+    JsonVariant variant = 0;
+    bool result = variant | true;
+    REQUIRE(result == true);
+  }
+
+  SECTION("const char* | const char*") {
+    JsonVariant variant = "not default";
+    std::string result = variant | "default";
+    REQUIRE(result == "not default");
+  }
+
+  SECTION("const char* | int") {
+    JsonVariant variant = "not default";
+    int result = variant | 42;
+    REQUIRE(result == 42);
+  }
+}