diff --git a/TinySTL/Test/AVLTreeTest.cpp b/TinySTL/Test/AVLTreeTest.cpp
index 9f140fb..de7b66c 100644
--- a/TinySTL/Test/AVLTreeTest.cpp
+++ b/TinySTL/Test/AVLTreeTest.cpp
@@ -54,6 +54,12 @@ namespace TinySTL{
 			v.erase(std::unique(v.begin(), v.end()), v.end());
 			assert(container_equal(avl, v));
 
+			for (auto i = 0; i != 20; ++i){
+				avl.erase(*avl.cbegin());
+				v.erase(v.begin());
+				assert(container_equal(avl, v));
+			}
+
 			tsAVL<int> avl1;
 			avl1.insert(v.begin(), v.end());
 			assert(container_equal(avl1, v));
diff --git a/TinySTL/Test/BinarySearchTreeTest.cpp b/TinySTL/Test/BinarySearchTreeTest.cpp
index e65ea9b..5710e32 100644
--- a/TinySTL/Test/BinarySearchTreeTest.cpp
+++ b/TinySTL/Test/BinarySearchTreeTest.cpp
@@ -45,6 +45,12 @@ namespace TinySTL{
 			v.erase(std::unique(v.begin(), v.end()), v.end());
 			assert(container_equal(bst, v));
 
+			for (auto i = 0; i != 20; ++i){
+				bst.erase(*bst.cbegin());
+				v.erase(v.begin());
+				assert(container_equal(bst, v));
+			}
+			
 			tsBst<int> bst1;
 			bst1.insert(v.begin(), v.end());
 			assert(container_equal(bst1, v));