zig/test/cases/enum_with_members.zig

const assert = @import("std").debug.assert;
const mem = @import("std").mem;
const fmt = @import("std").fmt;

const ET = union(enum) {
    SINT: i32,
    UINT: u32,

    pub fn print(a: &const ET, buf: []u8) -> %usize {
        return switch (*a) {
            ET.SINT => |x| { fmt.formatIntBuf(buf, x, 10, false, 0) },
            ET.UINT => |x| { fmt.formatIntBuf(buf, x, 10, false, 0) },
        }
    }
};

test "enum with members" {
    const a = ET { .SINT = -42 };
    const b = ET { .UINT = 42 };
    var buf: [20]u8 = undefined;

    assert(%%a.print(buf[0..]) == 3);
    assert(mem.eql(u8, buf[0..3], "-42"));

    assert(%%b.print(buf[0..]) == 2);
    assert(mem.eql(u8, buf[0..2], "42"));
}