grains is easy

rust/grains/tests/grains.rs

@@ -0,0 +1,52 @@
+use grains::*;
+
+#[test]
+fn grains_on_square_1() {
+    assert_eq!(square(1), 1);
+}
+
+#[test]
+fn grains_on_square_2() {
+    assert_eq!(square(2), 2);
+}
+
+#[test]
+fn grains_on_square_3() {
+    assert_eq!(square(3), 4);
+}
+
+#[test]
+fn grains_on_square_4() {
+    assert_eq!(square(4), 8);
+}
+
+#[test]
+fn grains_on_square_16() {
+    assert_eq!(square(16), 32_768);
+}
+
+#[test]
+fn grains_on_square_32() {
+    assert_eq!(square(32), 2_147_483_648);
+}
+
+#[test]
+fn grains_on_square_64() {
+    assert_eq!(square(64), 9_223_372_036_854_775_808);
+}
+
+#[test]
+#[should_panic]
+fn square_0_is_invalid() {
+    square(0);
+}
+
+#[test]
+#[should_panic]
+fn square_greater_than_64_is_invalid() {
+    square(65);
+}
+#[test]
+fn returns_the_total_number_of_grains_on_the_board() {
+    assert_eq!(grains::total(), 18_446_744_073_709_551_615);
+}