Integration tests

In the previous section, we checked that a part of our code works: now, we will check that the program as a whole works, by writing integration tests. These tests reside in the tests/ directory, so we start by creating it:

mkdir tests

In this directory, we can create a new file, tests/server.rs, in which we'll put the following content:

extern crate ftp;

use std::process::Command;
use std::thread;
use std::time::Duration;

use ftp::FtpStream;

We import the ftp crate which is an FTP client; it will be useful to test our FTP server. We need to add it in Cargo.toml as well:

[dev-dependencies]
ftp = "^2.2.1"

Here we see a new section, dev-dependencies: it contains the dependencies that are needed outside the main crate itself, like in the integration tests. By putting the dependency here and not in [dependencies], it won't be available in the main crate, which is what we want.

Let's go back to the file tests/server.rs and add a test function:

#[test]
fn test_pwd() {
    let child...