Added simple unit test

src/tohex.rs

@@ -58,3 +58,23 @@ pub fn hexdump(mut reader: Box<dyn io::Read>, length: usize) {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::{dump_to_chr, dump_to_hex};
+
+    #[test]
+    fn dump_to_chr_test() {
+        let mut buf = [0; 1];
+        assert_eq!("\u{1b}[38;5;8m.\u{1b}[39m", dump_to_chr(&mut buf[0..1]));
+    }
+
+    #[test]
+    fn dump_to_hex_test() {
+        let mut buf = [0; 1];
+        assert_eq!(
+            "\u{1b}[38;5;8m00\u{1b}[39m                                     ",
+            dump_to_hex(&mut buf[0..1])
+        );
+    }
+}