chore(examples): add examples to docs

Signed-off-by: Paul Spooren <mail@aparcar.org>

util/src/fd.rs

@@ -435,4 +435,12 @@ mod tests {
         assert!(matches!(file.write(&buf), Err(_)));
         Ok(())
     }
+
+    #[test]
+    fn test_nullfd_read_write() {
+        let nullfd = open_nullfd().unwrap();
+        let mut buf = vec![0u8; 16];
+        assert_eq!(rustix::io::read(&nullfd, &mut buf).unwrap(), 0);
+        assert!(rustix::io::write(&nullfd, b"test").is_err());
+    }
 }

util/src/option.rs

@@ -1,4 +1,15 @@
 /// A helper trait for turning any type value into `Some(value)`.
+///
+/// # Examples
+///
+/// ```
+/// use rosenpass_util::option::SomeExt;
+///
+/// let x = 42;
+/// let y = x.some();
+///
+/// assert_eq!(y, Some(42));
+/// ```
 pub trait SomeExt: Sized {
     /// Wraps the calling value in `Some()`.
     fn some(self) -> Option<Self> {

util/src/time.rs

@@ -5,6 +5,16 @@ use std::time::Instant;
 /// This is a simple wrapper around `std::time::Instant` that provides a
 /// convenient way to get the seconds elapsed since the creation of the
 /// `Timebase` instance.
+///
+/// # Examples
+///
+/// ```
+/// use rosenpass_util::time::Timebase;
+///
+/// let timebase = Timebase::default();
+/// let now = timebase.now();
+/// assert!(now > 0.0);
+/// ```
 
 #[derive(Clone, Debug)]
 pub struct Timebase(Instant);

util/src/zeroize/zeroized_ext.rs

@@ -1,6 +1,20 @@
 use zeroize::Zeroize;
 
 /// Extension trait providing a method for zeroizing a value and returning it
+///
+/// # Examples
+///
+/// ```rust
+/// use zeroize::Zeroize;
+/// use rosenpass_util::zeroize::ZeroizedExt;
+///
+/// let mut value = String::from("hello");
+/// value.zeroize();
+/// assert_eq!(value, "");
+///
+/// let value = String::from("hello").zeroized();
+/// assert_eq!(value, "");
+/// ```
 pub trait ZeroizedExt: Zeroize + Sized {
     /// Zeroizes the value in place and returns self
     fn zeroized(mut self) -> Self {