Unit Tests

Mark unit tests with #[test]:

1. fn first_word(text: &str) -> &str {
2. match text.find(' ') {
3. Some(idx) => &text[..idx],
4. None => &text,
5. }
6. }

8. #[test]
9. fn test_empty() {
10. assert_eq!(first_word(""), "");
11. }

13. #[test]
14. fn test_single_word() {
15. assert_eq!(first_word("Hello"), "Hello");
16. }

18. #[test]
19. fn test_multiple_words() {
20. assert_eq!(first_word("Hello World"), "Hello");
21. }

Use cargo test to find and run the unit tests.