Second functionality is completed. Tests and comments included.

handler_test.go

@@ -56,5 +56,14 @@ func TestOpenDirectory(t *testing.T) {
 	assertEqual(t, len(result), 5, "")
 	assertEqual(t, result[0], "testFolder1", "")
 	assertEqual(t, result[1], "testFolder2", "")
+}
 
+/*
+Test if the tree function works by observing the counter.
+*/
+func TestTree(t *testing.T) {
+	counter := new(Counter)
+	tree("", counter, ".")
+	assertEqual(t, counter.directories, 3, "")
+	assertEqual(t, counter.files, 12, "")
 }