diff --git a/src/ext.rs b/src/ext.rs
index 3c69061..8af87ac 100644
--- a/src/ext.rs
+++ b/src/ext.rs
@@ -5,16 +5,19 @@ use std::{
     },
 };
 
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct HexSlice<'a>(&'a [u8]);
 
 impl<'a> HexSlice<'a>
 {
+    /// Create a new `HexSlice` wrapper
     #[inline] pub fn new<T>(from: &'a T) -> Self
     where T: AsRef<[u8]> + ?Sized + 'a
     {
 	Self(from.as_ref())
     }
 
+    /// Create a hex string output
     pub fn to_hex_string(&self) -> String
     {
 	
@@ -60,3 +63,18 @@ impl AsRef<[u8]> for HexSlice<'_>
 	self.0
     }
 }
+
+#[cfg(test)]
+mod tests
+{
+    use super::*;
+    #[test]
+    fn hex_encode_bytes()
+    {
+	let input = b"hello world";
+	let output = input.as_hex();
+	assert_eq!("68656c6c6f20776f726c64", output.to_hex_string());
+	assert_eq!(input.as_hex(), output.as_hex());
+	assert_eq!(format!("{}", output), "68656c6c6f20776f726c64");
+    }
+}