Add memoryUsage() to ElementProxy and MemberProxy (fixes #1730)

extras/tests/JsonDocument/DynamicJsonDocument.cpp

@@ -205,4 +205,26 @@ TEST_CASE("DynamicJsonDocument assignment") {
     REQUIRE_JSON(doc2, "42");
     REQUIRE(doc2.capacity() == 4096);
   }
+
+  SECTION("Assign from MemberProxy") {
+    StaticJsonDocument<200> doc1;
+    doc1["value"] = 42;
+
+    DynamicJsonDocument doc2(4096);
+    doc2 = doc1["value"];
+
+    REQUIRE_JSON(doc2, "42");
+    REQUIRE(doc2.capacity() == 4096);
+  }
+
+  SECTION("Assign from ElementProxy") {
+    StaticJsonDocument<200> doc1;
+    doc1[0] = 42;
+
+    DynamicJsonDocument doc2(4096);
+    doc2 = doc1[0];
+
+    REQUIRE_JSON(doc2, "42");
+    REQUIRE(doc2.capacity() == 4096);
+  }
 }

extras/tests/JsonDocument/ElementProxy.cpp

@@ -188,6 +188,21 @@ TEST_CASE("ElementProxy::size()") {
   }
 }
 
+TEST_CASE("ElementProxy::memoryUsage()") {
+  DynamicJsonDocument doc(4096);
+  doc.addElement();
+  ElementProxy<JsonDocument&> ep = doc[0];
+
+  SECTION("returns 0 for null") {
+    REQUIRE(ep.memoryUsage() == 0);
+  }
+
+  SECTION("returns size for string") {
+    ep.set(std::string("hello"));
+    REQUIRE(ep.memoryUsage() == 6);
+  }
+}
+
 TEST_CASE("ElementProxy::operator[]") {
   DynamicJsonDocument doc(4096);
   ElementProxy<JsonDocument&> ep = doc[1];

extras/tests/JsonDocument/MemberProxy.cpp

@@ -229,6 +229,20 @@ TEST_CASE("MemberProxy::size()") {
   }
 }
 
+TEST_CASE("MemberProxy::memoryUsage()") {
+  DynamicJsonDocument doc(4096);
+  MemberProxy<JsonDocument &, const char *> mp = doc["hello"];
+
+  SECTION("returns 0 when null") {
+    REQUIRE(mp.memoryUsage() == 0);
+  }
+
+  SECTION("return the size for a string") {
+    mp.set(std::string("hello"));
+    REQUIRE(mp.memoryUsage() == 6);
+  }
+}
+
 TEST_CASE("MemberProxy::operator[]") {
   DynamicJsonDocument doc(4096);
   MemberProxy<JsonDocument &, const char *> mp = doc["hello"];