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Getting Started with Rust (Hello World, Mac)

In this article, I'm going to show you how to install the tools to create and run a Hello World app using Rust.

info

These instructions were written and tested on a Mac.

Step 1. Install rustc and cargo​

The first thing you should do is see if you have the necessary tools installed already.

  • Open the Terminal application on your Mac

You can find it in the Applications > Utilities folder.

  • Check if you have rustc and cargo installed by typing the following commands in the Terminal:
rustc --version
cargo --version

If rustc and cargo are not installed:

On a Mac, you can install them using brew with this command:

brew install rustup

You may see this message at the end of the install:

Please run `rustup-init` to initialize `rustup` and install other Rust components.
  • Run it:
rustup-init
  • Select the default option

When the install finishes, follow the instructions to source your shell and update your path (or just close the terminal window and open a new one).

For example (note the starting dot):

. "$HOME/.cargo/env"
  • Verify everything was installed:
rustc --version
cargo --version

Step 2. Create a Rust projects root folder​

In a terminal window, run the following commands:

mkdir -p ~/projects/rust/
cd ~/projects/rust/

Step 3. Create a Rust project​

In Rust, projects are managed using Cargo, which automates tasks such as dependency management, building, and testing.

  • Make sure you are in the root of your Rust projects folder:
cd ~/projects/rust/
  • Run cargo to create a new project:
cargo new rust-101

The command should have created a new directory named rust-101

It should contain a basic Rust project structure.

  • Switch to the folder and view the contents:
cd rust-101
ls -ls
tip

If you prefer to create the folder first, you could have done something like this instead:

mkdir -p ~/projects/rust/rust-altway
cd ~/projects/rust/rust-altway
cargo init .
ls -ls

The result would have been the same.

Step 4. Review the generated code​

The new project should already contain a default program.

  • Open src/main.rs and verify that it looks like this:
fn main() {
    println!("Hello, world!");
}

Feel free to change the message.

  • The default code defines a main function that prints "Hello, world!" to the console.

Step 5. Build the program​

You can build the program to run using cargo.

  • From the root of your project folder, run the following:
cargo build

The cargo build command will compile your Rust code and create an executable binary in the target/debug directory.

ls -ls target/debug

Step 6. Run the program​

You can run the binary directly like this:

 target/debug/rust-101

You can run it with a bit more debug info, using cargo like this:

cargo run

Or more quietly using cargo like this:

cargo run --quiet

Congratulations! You've successfully created, built, and run your first Rust program!

Now let's add some tests to make sure that our code runs as expected.

Step 7. Testing​

Rust has a built-in testing framework that makes it easy to write and run tests for your code. Follow these steps to add tests to your "Hello, World!" program:

  • Open the src/main.rs file in your editor
  • Add the following test function below the main function and save the file:
#[cfg(test)]
mod tests {
    use std::process::Command;

    #[test]
    fn test_hello_world_output() {
        let output = Command::new("cargo")
                             .arg("run")
                             .arg("--quiet")
                             .output()
                             .expect("Failed to run command");

        let stdout = String::from_utf8(output.stdout).expect("Invalid UTF-8 in stdout");
        let stderr = String::from_utf8(output.stderr).expect("Invalid UTF-8 in stderr");

        assert!(output.status.success(), "Command failed with: {}", stderr);

        assert_eq!(stdout.trim(), "Hello, world!");
    }
}

This test function checks that the main function prints "Hello, world!" to the console as expected. Edit the expectation if you changed the default message.

Step 8. Run the test​

To run the tests, you can use cargo again.

  • From the root of your project, run this command:
cargo test

Cargo will compile your code and execute the test function.

If everything is working correctly, you should see a message indicating that the one test passed.

Example​

You can find the code for this article here:

Conclusion​

In this article, you learned how to:

  • Install the tools for working with Rust on a Mac
  • Create, build, and test a Rust "Hello, World!" program

References​