exercises(grains): assert, rather than returning error union

config.json

@@ -190,17 +190,17 @@
         "slug": "grains",
         "name": "Grains",
         "practices": [
+          "asserting",
           "bitwise-operations",
           "builtin-functions",
           "conditionals",
-          "error-sets",
           "functions"
         ],
         "prerequisites": [
+          "asserting",
           "bitwise-operations",
           "builtin-functions",
           "conditionals",
-          "error-sets",
           "functions"
         ],
         "difficulty": 1

exercises/practice/grains/.meta/example.zig

@@ -1,17 +1,11 @@
 const std = @import("std");
-const math = std.math;
 
-pub const ChessboardError = error{IndexOutOfBounds};
-
-const number_of_chess_squares = 64;
-
-pub fn square(index: usize) ChessboardError!u64 {
-    if (index > number_of_chess_squares or index == 0) {
-        return ChessboardError.IndexOutOfBounds;
-    }
+/// Asserts that `index` is greater than 0 and less than 65.
+pub fn square(index: u7) u64 {
+    std.debug.assert(index > 0 and index < 65);
     return @as(u64, 1) << @as(u6, @truncate(index - 1));
 }
 
 pub fn total() u64 {
-    return math.maxInt(u64);
+    return std.math.maxInt(u64);
 }

exercises/practice/grains/.meta/tests.toml

@@ -32,13 +32,15 @@ description = "returns the number of grains on the square -> grains on square 64
 
 [1d47d832-3e85-4974-9466-5bd35af484e3]
 description = "returns the number of grains on the square -> square 0 raises an exception"
+include = false
 
 [61974483-eeb2-465e-be54-ca5dde366453]
 description = "returns the number of grains on the square -> negative square raises an exception"
 include = false
 
 [a95e4374-f32c-45a7-a10d-ffec475c012f]
 description = "returns the number of grains on the square -> square greater than 64 raises an exception"
+include = false
 
 [6eb07385-3659-4b45-a6be-9dc474222750]
 description = "returns the total number of grains on the board"

exercises/practice/grains/grains.zig

@@ -1,4 +1,5 @@
-pub fn square(index: usize) ChessboardError!u64 {
+/// Asserts that `index` is greater than 0 and less than 65.
+pub fn square(index: usize) u64 {
     _ = index;
     @compileError("please implement the square function");
 }

exercises/practice/grains/test_grains.zig

@@ -2,62 +2,49 @@ const std = @import("std");
 const testing = std.testing;
 
 const grains = @import("grains.zig");
-const ChessboardError = grains.ChessboardError;
 
 test "grains on square 1" {
     const expected: u64 = 1;
-    const actual = try grains.square(1);
+    const actual = grains.square(1);
     try testing.expectEqual(expected, actual);
 }
 
 test "grains on square 2" {
     const expected: u64 = 2;
-    const actual = try grains.square(2);
+    const actual = grains.square(2);
     try testing.expectEqual(expected, actual);
 }
 
 test "grains on square 3" {
     const expected: u64 = 4;
-    const actual = try grains.square(3);
+    const actual = grains.square(3);
     try testing.expectEqual(expected, actual);
 }
 
 test "grains on square 4" {
     const expected: u64 = 8;
-    const actual = try grains.square(4);
+    const actual = grains.square(4);
     try testing.expectEqual(expected, actual);
 }
 
 test "grains on square 16" {
     const expected: u64 = 32_768;
-    const actual = try grains.square(16);
+    const actual = grains.square(16);
     try testing.expectEqual(expected, actual);
 }
 
 test "grains on square 32" {
     const expected: u64 = 2_147_483_648;
-    const actual = try grains.square(32);
+    const actual = grains.square(32);
     try testing.expectEqual(expected, actual);
 }
 
 test "grains on square 64" {
     const expected: u64 = 9_223_372_036_854_775_808;
-    const actual = try grains.square(64);
+    const actual = grains.square(64);
     try testing.expectEqual(expected, actual);
 }
 
-test "square 0 produces an error" {
-    const expected = ChessboardError.IndexOutOfBounds;
-    const actual = grains.square(0);
-    try testing.expectError(expected, actual);
-}
-
-test "square greater than 64 produces an error" {
-    const expected = ChessboardError.IndexOutOfBounds;
-    const actual = grains.square(65);
-    try testing.expectError(expected, actual);
-}
-
 test "returns the total number of grains on the board" {
     const expected: u64 = 18_446_744_073_709_551_615;
     const actual = grains.total();