feat(rust): add likes kata

rust/tests/5_likes.rs

@@ -0,0 +1,79 @@
+fn likes(names: &[&str]) -> String {
+    match names {
+        [] => format!("no one likes this"),
+        [a] => format!("{} likes this", a),
+        [a, b] => format!("{} and {} like this", a, b),
+        [a, b, c] => format!("{}, {} and {} like this", a, b, c),
+        [a, b, rest @ ..] => format!("{}, {} and {} others like this", a, b, rest.len()),
+    }
+}
+#[cfg(test)]
+mod tests {
+    use super::likes;
+
+    #[test]
+    fn fixed_tests() {
+        assert_eq!(likes(&[]), "no one likes this");
+        assert_eq!(likes(&["Peter"]), "Peter likes this");
+        assert_eq!(likes(&["Jacob", "Alex"]), "Jacob and Alex like this");
+        assert_eq!(
+            likes(&["Max", "John", "Mark"]),
+            "Max, John and Mark like this"
+        );
+        assert_eq!(
+            likes(&["Alex", "Jacob", "Mark", "Max"]),
+            "Alex, Jacob and 2 others like this"
+        );
+        assert_eq!(
+            likes(&["a", "b", "c", "d", "e"]),
+            "a, b and 3 others like this"
+        );
+    }
+
+    #[test]
+    fn random_tests() {
+        use rand::{seq::SliceRandom, thread_rng, Rng};
+
+        let mut rng = thread_rng();
+
+        let mut base = vec![
+            "Sylia Stingray",
+            "Priscilla S. Asagiri",
+            "Linna Yamazaki",
+            "Nene Romanova",
+            "Nigel",
+            "Macky Stingray",
+            "Largo",
+            "Brian J. Mason",
+            "Sylvie",
+            "Anri",
+            "Leon McNichol",
+            "Daley Wong",
+            "Galatea",
+            "Quincy Rosenkreutz",
+        ];
+
+        for _ in 0..100 {
+            base.shuffle(&mut rng);
+            let len = rng.gen_range(0..base.len());
+            let names = base.iter().take(len).cloned().collect::<Vec<_>>();
+
+            let actual = likes(&names);
+            let expect = likes_solution(&names);
+
+            assert_eq!(actual, expect);
+        }
+    }
+
+    fn likes_solution(names: &[&str]) -> String {
+        let l = names.len();
+
+        match l {
+            0 => "no one likes this".to_owned(),
+            1 => format!("{} likes this", names[0]),
+            2 => format!("{} and {} like this", names[0], names[1]),
+            3 => format!("{}, {} and {} like this", names[0], names[1], names[2]),
+            _ => format!("{}, {} and {} others like this", names[0], names[1], l - 2),
+        }
+    }
+}