diff --git a/codecov.yml b/codecov.yml
index c6a9a0b7..de3bbcd5 100644
--- a/codecov.yml
+++ b/codecov.yml
@@ -23,4 +23,6 @@ ignore:
   - "third_party/catch.hpp"
   - "third_party/json.hpp"
   - "third_party/matplotlibcpp.h"
-  - "src/visualization/*"
+  - "src/visualization/graph_visual/graph_visualization.h"
+  - "src/visualization/list_visual/list_visualization.h"
+  - "src/visualization/tree_visual/tree_visualization.h"
diff --git a/tests/linalg/mat1d/mat_1d.cc b/tests/linalg/mat1d/mat_1d.cc
index 42e9edf5..d8410f52 100644
--- a/tests/linalg/mat1d/mat_1d.cc
+++ b/tests/linalg/mat1d/mat_1d.cc
@@ -114,6 +114,14 @@ TEST_CASE("Testing != operator for Mat1d class") {
     REQUIRE(mat3 != mat4);
 }
 
+TEST_CASE("Testing operator << for Mat1d class") {
+    Mat1d<int, 5> mat({1, 2, 3, 4, 5});
+    CHECK_NOTHROW(std::cout << mat << '\n');
+
+    Mat1d<char, 5> mat2({'a', 'b', 'c', 'd', 'e'});
+    CHECK_NOTHROW(std::cout << mat2 << '\n');
+}
+
 // TEST_CASE("testing constructor with one value for Mat1d class [1]") {
 //     Mat1d<int, 5> mat(5);
 //     for(auto it = mat.begin(); it != mat.end(); it++){