put tests fn in here

src/main.rs

@@ -1,5 +1,13 @@
 pub mod graph;
 
-fn main() {
-    graph::tests("graph");
+pub fn main() {
+    tests("graph")
 }
+
+pub fn tests(arg: &str) {
+    match arg {
+        "graph" => graph::test(),
+        "matrix" => graph::matrix::test(),
+        &_ => println!("{arg} is not a valid option"),
+    }
+}