feat(rust): add bishop kata

rust/tests/6_bishop.rs

@@ -0,0 +1,52 @@
+// 8 |_|#|_|#|_|#|_|#|
+// 7 |#|_|#|_|#|_|#|_|
+// 6 |_|#|_|#|_|#|_|#|
+// 5 |#|_|#|_|#|_|#|_|
+// 4 |_|#|_|#|_|#|_|#|
+// 3 |#|_|#|_|#|_|#|_|
+// 2 |_|#|_|#|_|#|_|#|
+// 1 |#|_|#|_|#|_|#|_|
+//    a b c d e f g h
+
+fn bishop(start_pos: &str, end_pos: &str, num_moves: u8) -> bool {
+    let (x1, y1) = get_coords(start_pos);
+    let (x2, y2) = get_coords(end_pos);
+
+    let is_same_position = start_pos == end_pos;
+    let is_same_color = (x1 + y1) % 2 == (x2 + y2) % 2;
+    let is_same_line = (x1 - x2).abs() == (y1 - y2).abs();
+
+    match num_moves {
+        0 => is_same_position,
+        1 => is_same_line,
+        _ => is_same_color,
+    }
+}
+
+fn get_coords(pos: &str) -> (i8, i8) {
+    let mut chars = pos.chars();
+    let x = chars.next().unwrap() as i8 - ('a' as i8);
+    let y = chars.next().unwrap() as i8 - ('1' as i8);
+    (x, y)
+}
+
+#[test]
+fn test_basic() {
+    assert_eq!(bishop("a1", "b4", 2), true);
+    assert_eq!(bishop("a1", "b4", 2), true);
+    assert_eq!(bishop("a1", "b5", 5), false);
+    assert_eq!(bishop("f1", "f1", 0), true);
+    assert_eq!(bishop("e6", "a1", 2), false);
+    assert_eq!(bishop("h2", "a2", 1), false);
+    assert_eq!(bishop("d1", "a3", 1), false);
+    assert_eq!(bishop("b2", "a4", 2), false);
+    assert_eq!(bishop("d7", "a5", 0), false);
+    assert_eq!(bishop("e7", "a6", 2), false);
+    assert_eq!(bishop("d1", "a7", 1), false);
+    assert_eq!(bishop("c6", "a8", 2), true);
+    assert_eq!(bishop("d7", "b1", 1), false);
+    assert_eq!(bishop("e5", "b2", 2), true);
+    assert_eq!(bishop("c7", "b3", 0), false);
+    assert_eq!(bishop("b4", "b4", 1), true);
+    assert_eq!(bishop("h5", "b5", 1), false);
+}