Fix inconsistent Node::size when removing a key with unassigned node (#327) (#449)

include/yaml-cpp/node/detail/impl.h

@@ -132,6 +132,14 @@ inline bool node_data::remove(const Key& key, shared_memory_holder pMemory) {
   if (m_type != NodeType::Map)
     return false;
 
+  kv_pairs::iterator it = m_undefinedPairs.begin();
+  while (it != m_undefinedPairs.end()) {
+    kv_pairs::iterator jt = std::next(it);
+    if (it->first->equals(key, pMemory))
+      m_undefinedPairs.erase(it);
+    it = jt;
+  }
+
   for (node_map::iterator it = m_map.begin(); it != m_map.end(); ++it) {
     if (it->first->equals(key, pMemory)) {
       m_map.erase(it);

test/node/node_test.cpp

@@ -88,6 +88,13 @@ TEST(NodeTest, MapWithUndefinedValues) {
   EXPECT_EQ(2, node.size());
 }
 
+TEST(NodeTest, RemoveUnassignedNode) {
+  Node node(NodeType::Map);
+  node["key"];
+  node.remove("key");
+  EXPECT_EQ(node.size(), 0);
+}
+
 TEST(NodeTest, MapForceInsert) {
   Node node;
   Node k1("k1");