meta: improve library and cli tests coverage

[jeertmans]

What

Currently, only a few functions are tested, which may lead to uncaught breaking changes in the future.

With the issue, I hope to motivate the need of creating more tests to extend the actual coverage.

How to

Testing library

For testing individual functions, you can create tests either inside tests modules, e.g., with mod tests (or test_my_name):

languagetool-rust/src/lib/server.rs

Lines 562 to 594 in 6cf960a

	#[cfg(test)]
	mod tests {
	use crate::check::CheckRequest;
	use crate::ServerClient;
	#[tokio::test]
	async fn test_server_ping() {
	let client = ServerClient::from_env_or_default();
	assert!(client.ping().await.is_ok());
	}
	#[tokio::test]
	async fn test_server_check_text() {
	let client = ServerClient::from_env_or_default();
	let req = CheckRequest::default().with_text("je suis une poupee".to_owned());
	assert!(client.check(&req).await.is_ok());
	}
	#[tokio::test]
	async fn test_server_check_data() {
	let client = ServerClient::from_env_or_default();
	let req = CheckRequest::default()
	.with_data_str("{\"annotation\":[{\"text\": \"je suis une poupee\"}]}")
	.unwrap();
	assert!(client.check(&req).await.is_ok());
	}
	#[tokio::test]
	async fn test_server_languages() {
	let client = ServerClient::from_env_or_default();
	assert!(client.languages().await.is_ok());
	}
	}

or inside function's documentation, e.g, with examples:

languagetool-rust/src/lib/server.rs

Lines 24 to 47 in 6cf960a

	/// Check if `v` is a valid port.
	///
	/// A valid port is either
	/// - an empty string
	/// - a 4 chars long string with each char in [0-9]
	///
	/// # Examples
	///
	/// ```
	/// # use languagetool_rust::server::is_port;
	/// assert!(is_port("8081").is_ok());
	///
	/// assert!(is_port("").is_ok()); // No port specified, which is accepted
	///
	/// assert!(is_port("abcd").is_err());
	/// ```
	pub fn is_port(v: &str) -> Result<()> {
	if v.is_empty() || (v.len() == 4 && v.chars().all(char::is_numeric)) {
	return Ok(());
	}
	Err(Error::InvalidValue {
	body: "The value should be a 4 characters long string with digits only".to_owned(),
	})
	}

for testing multiple functions at the same time, i.e., the integration of multiple functions, please write tests in the tests folder.

Testing the CLI

Testing the CLI is the same as for the library, but everything is currently defined the src/bin.rs. So you should test build_cli() with different arguments and check that it correctly fails or succeed for some configurations. See clap::Command::try_get_matches_from.