Use cargo doc to build documentation in target/doc.

Use cargo test to run all tests (including documentation tests), and cargo test --doc to only run documentation tests.

These commands will appropriately invoke rustdoc (and rustc) as required.

Doc comments

Doc comments are very useful for big projects that require documentation. When running Rustdoc, these are the comments that get compiled into documentation. They are denoted by a ///, and support Markdown.

#![crate_name = "doc"]

/// A human being is represented here
pub struct Person {
    /// A person must have a name, no matter how much Juliet may hate it
    name: String,

impl Person {
    /// Returns a person with the name given them
    /// # Arguments
    /// * `name` - A string slice that holds the name of the person
    /// # Example
    /// ```
    /// // You can have rust code between fences inside the comments
    /// // If you pass --test to Rustdoc, it will even test it for you!
    /// use doc::Person;
    /// let person = Person::new("name");
    /// ```
    pub fn new(name: &str) -> Person {
        Person {
            name: name.to_string(),

    /// Gives a friendly hello!
    /// Says "Hello, [name]" to the `Person` it is called on.
    pub fn hello(& self) {
        println!("Hello, {}!",;

fn main() {
    let john = Person::new("John");


To run the tests, first build the code as a library, then tell rustdoc where to find the library so it can link it into each doctest program:

$ rustc --crate-type lib
$ rustdoc --test --extern doc="libdoc.rlib"

See also: