diff --git a/rustbyexample/hello/testcase_list.rs b/rustbyexample/hello/testcase_list.rs
new file mode 100644
index 0000000..2f29761
--- /dev/null
+++ b/rustbyexample/hello/testcase_list.rs
@@ -0,0 +1,23 @@
+use std::fmt;
+
+struct List(Vec<i32>);
+
+impl fmt::Display for List {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let vec = &self.0;
+
+        write!(f, "[")?;
+
+        for (count, v ) in vec.iter().enumerate() {
+            if count != 0 { write!(f, ", ")?; }
+            write!(f, "{}", v)?;
+        }
+
+        write!(f, "]")
+    }
+}
+
+fn main() {
+    let v = List(vec![1, 2, 3]);
+    println!("{}", v);
+}