diff --git a/tests/tree/avl.cc b/tests/tree/avl.cc
index 1752d9fa..8ead82d6 100644
--- a/tests/tree/avl.cc
+++ b/tests/tree/avl.cc
@@ -164,6 +164,14 @@ TEST_CASE("Testing get_root function in avl tree"){
   REQUIRE(t.get_root() == 36);
 }
 
+TEST_CASE("Testing operator << for avl tree") {
+    avl_tree<int> t({1, 10, 2, 8, 6, 5});
+    REQUIRE_NOTHROW(cout << t);
+
+    avl_tree<char> tt({'a', 'g', 'd', 'z', 'w', 'f'});
+    REQUIRE_NOTHROW(cout << tt);
+}
+
 #define TREE_VISUALIZATION_H
 #ifdef TREE_VISUALIZATION_H
 
diff --git a/tests/tree/bst.cc b/tests/tree/bst.cc
index 9a260aa2..830b3e50 100644
--- a/tests/tree/bst.cc
+++ b/tests/tree/bst.cc
@@ -151,6 +151,14 @@ TEST_CASE("testing level order in bst"){
   REQUIRE(produced == sol);
 }
 
+TEST_CASE("Testing opearator << for bst") {
+    bst<int> t({1, 10, 5, 3, 9, 25});
+    REQUIRE_NOTHROW(cout << t);
+
+    bst<char> tt({'a', 'g', 'q', 'v', 'w'});
+    REQUIRE_NOTHROW(cout << tt);
+}
+
 #define TREE_VISUALIZATION_H
 #ifdef TREE_VISUALIZATION_H
 
diff --git a/tests/tree/splay_tree.cc b/tests/tree/splay_tree.cc
index 04e2926e..01b8a754 100644
--- a/tests/tree/splay_tree.cc
+++ b/tests/tree/splay_tree.cc
@@ -128,6 +128,14 @@ TEST_CASE("testing level order for splay tree"){
   REQUIRE(produced==sol);
 }
 
+TEST_CASE("Testing operator << for splay tree") {
+    splay_tree<int> t({1, 5, 3, 2, 9, 11});
+    REQUIRE_NOTHROW(cout << t);
+
+    splay_tree<char> tt({'a', 'b', 'w', 'z', 'f', 'd'});
+    REQUIRE_NOTHROW(cout << tt);
+}
+
 #define TREE_VISUALIZATION_H
 #ifdef TREE_VISUALIZATION_H
 
diff --git a/tests/tree/tree.cc b/tests/tree/tree.cc
index d0de6f33..138888f4 100644
--- a/tests/tree/tree.cc
+++ b/tests/tree/tree.cc
@@ -53,6 +53,27 @@ TEST_CASE("testing level order traversal in tree class [TREECLASS]"){
   REQUIRE(produced == sol);
 }
 
+TEST_CASE("Testing operator << for tree") {
+    tree<int> t;
+    t.insert("", 1);
+    t.insert("l", 2);
+    t.insert("r", 3);
+    t.insert("ll", 4);
+    t.insert("lr", 5);
+    t.insert("rl", 6);
+    t.insert("rr", 7);
+    t.insert("lll", 8);
+    t.insert("llr", 9);
+    t.insert("lrl", 10);
+    REQUIRE_NOTHROW(cout << t);
+
+    tree<std::string> tt;
+    tt.insert("", "hello");
+    tt.insert("r", "world");
+    tt.insert("l", "universe");
+    REQUIRE_NOTHROW(cout << tt);
+}
+
 #define TREE_VISUALIZATION_H
 #ifdef TREE_VISUALIZATION_H