JsonArray::remove() and JsonObject::remove() now release the memory of the variant

test/DynamicMemoryPool/CMakeLists.txt

@@ -4,6 +4,7 @@
 
 add_executable(DynamicMemoryPoolTests 
 	alloc.cpp
+	allocSlot.cpp
 	no_memory.cpp
 	size.cpp
 	startString.cpp

test/DynamicMemoryPool/allocSlot.cpp

@@ -0,0 +1,27 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2018
+// MIT License
+
+#include <ArduinoJson/Memory/DynamicMemoryPool.hpp>
+#include <catch.hpp>
+
+using namespace ARDUINOJSON_NAMESPACE;
+
+TEST_CASE("DynamicMemoryPool::allocSlot()") {
+  DynamicMemoryPool memoryPool;
+
+  SECTION("Returns different pointer") {
+    Slot* s1 = memoryPool.allocSlot();
+    Slot* s2 = memoryPool.allocSlot();
+
+    REQUIRE(s1 != s2);
+  }
+
+  SECTION("Returns same pointer after freeSlot()") {
+    Slot* s1 = memoryPool.allocSlot();
+    memoryPool.freeSlot(s1);
+    Slot* s2 = memoryPool.allocSlot();
+
+    REQUIRE(s1 == s2);
+  }
+}

test/DynamicMemoryPool/size.cpp

@@ -26,4 +26,23 @@ TEST_CASE("DynamicMemoryPool::size()") {
     memoryPool.clear();
     REQUIRE(0 == memoryPool.size());
   }
+
+  SECTION("Increases after allocSlot()") {
+    memoryPool.allocSlot();
+    REQUIRE(sizeof(Slot) == memoryPool.size());
+
+    memoryPool.allocSlot();
+    REQUIRE(2 * sizeof(Slot) == memoryPool.size());
+  }
+
+  SECTION("Decreases after freeSlot()") {
+    Slot* s1 = memoryPool.allocSlot();
+    Slot* s2 = memoryPool.allocSlot();
+
+    memoryPool.freeSlot(s1);
+    REQUIRE(sizeof(Slot) == memoryPool.size());
+
+    memoryPool.freeSlot(s2);
+    REQUIRE(0 == memoryPool.size());
+  }
 }

test/JsonDocument/DynamicJsonDocument.cpp

@@ -92,4 +92,66 @@ TEST_CASE("DynamicJsonDocument") {
     REQUIRE(json == "{\"hello\":\"world\"}");
     REQUIRE(ddoc.nestingLimit == 42);
   }
+
+  SECTION("memoryUsage()") {
+    typedef ARDUINOJSON_NAMESPACE::Slot Slot;
+
+    SECTION("Increases after adding value to array") {
+      JsonArray arr = doc.to<JsonArray>();
+
+      arr.add(42);
+      REQUIRE(sizeof(Slot) == doc.memoryUsage());
+      arr.add(43);
+      REQUIRE(2 * sizeof(Slot) == doc.memoryUsage());
+    }
+
+    SECTION("Decreases after remove value from array") {
+      JsonArray arr = doc.to<JsonArray>();
+      arr.add(42);
+      arr.add(43);
+
+      arr.remove(1);
+      REQUIRE(sizeof(Slot) == doc.memoryUsage());
+      arr.remove(0);
+      REQUIRE(0 == doc.memoryUsage());
+    }
+
+    SECTION("Increases after adding value to object") {
+      JsonObject obj = doc.to<JsonObject>();
+
+      obj["a"] = 1;
+      REQUIRE(sizeof(Slot) == doc.memoryUsage());
+      obj["b"] = 2;
+      REQUIRE(2 * sizeof(Slot) == doc.memoryUsage());
+    }
+
+    SECTION("Decreases after removing value from object") {
+      JsonObject obj = doc.to<JsonObject>();
+      obj["a"] = 1;
+      obj["b"] = 2;
+
+      obj.remove("a");
+      REQUIRE(sizeof(Slot) == doc.memoryUsage());
+      obj.remove("b");
+      REQUIRE(0 == doc.memoryUsage());
+    }
+
+    SECTION("Decreases after removing nested object from array") {
+      JsonArray arr = doc.to<JsonArray>();
+      JsonObject obj = arr.createNestedObject();
+      obj["hello"] = "world";
+
+      arr.remove(0);
+      REQUIRE(0 == doc.memoryUsage());
+    }
+
+    SECTION("Decreases after removing nested array from object") {
+      JsonObject obj = doc.to<JsonObject>();
+      JsonArray arr = obj.createNestedArray("hello");
+      arr.add("world");
+
+      obj.remove("hello");
+      REQUIRE(0 == doc.memoryUsage());
+    }
+  }
 }