A BF in zig (beggining)

bg.zig

const std = @import("std");

const MEMORY_SIZE :i32 = 30_000;

fn execute(program: []const u8) [MEMORY_SIZE]i8 {
    var memory :[MEMORY_SIZE]i8 = [_]i8{0} ** MEMORY_SIZE;
    var memory_index: u32 = 0;
    var output = std.ArrayList(u8).init(std.heap.page_allocator);
    defer output.deinit();

    for (program) |command| {
        switch (command) {
            '+' => { memory[memory_index] += 1; },
            '-' => { memory[memory_index] -= 1; },
            '.' => { try output.append(@intCast(u8, memory[memory_index])); },
            '>' => {
                if(memory_index < MEMORY_SIZE-1) {
                    memory_index += 1;
                } else {
                    memory_index = 0;
                }
            },
            '<' => {
                 if(memory_index > 0) {
                    memory_index -= 1;
                } else {
                    memory_index = MEMORY_SIZE-1;
                }
             },
            else => {},
        }
    }

    return memory;
}

test "Advance then add 1" {
    var result :[MEMORY_SIZE]i8 = undefined;

    result = execute(">+");
    std.testing.expect(result[1] == 1);
}

// test if go to index -1
test "Step back and add 1" {
    var result :[MEMORY_SIZE]i8 = undefined;

    result = execute("<+");
    std.testing.expect(result[MEMORY_SIZE-1] == 1);
}

test "Try a buffer overflow" {
    var result :[MEMORY_SIZE]i8 = undefined;

    result = execute("<>+");
    std.testing.expect(result[0] == 1);
}