All the Rust code samples in documentation are tested by default.

/// Manipulate a number by magic
///
/// # Examples
///
/// ```rust
/// assert_eq!(min( 0,   14),    0);
/// assert_eq!(min( 0, -127), -127);
/// assert_eq!(min(42,  666),   42);
/// ```
fn min(lhs: i32, rhs: i32) -> i32 {
	if lhs < rhs { lhs } else { rhs }
}

To compile but not run a code block, use no_run:

/// Example
///
/// ```no_run
/// use std::fs::File;
///
/// let mut f = File::open("some_file.txt").expect("failed");
/// ```
pub fn item() {}

If you want a code block to considered as a Rust one (for the syntax highlighting) but don’t want to compile it, you can use ignore:

/// Example
///
/// ```ignore
/// hello!
/// ```
pub fn item() {}

To show a code example that fails to compile, use compile_fail.

Hide Lines

We can hide some lines from code example display by using #:

/// Example
///
/// ```no_run
/// use std::fs::File;
///
/// # fn foo() -> std::io::Result<()> {
/// let mut f = File::create("foo.txt")?;
/// # Ok(())
/// # }
/// ```
pub fn item() {}

The code example will look like this:

use std::fs::File;
 
let mut f = File::create("foo.txt")?;

Reference