zig/doc/langref/test_integer_widening.zig

const std = @import("std");
const builtin = @import("builtin");
const expect = std.testing.expect;
const mem = std.mem;

test "integer widening" {
    const a: u8 = 250;
    const b: u16 = a;
    const c: u32 = b;
    const d: u64 = c;
    const e: u64 = d;
    const f: u128 = e;
    try expect(f == a);
}

test "implicit unsigned integer to signed integer" {
    const a: u8 = 250;
    const b: i16 = a;
    try expect(b == 250);
}

test "float widening" {
    const a: f16 = 12.34;
    const b: f32 = a;
    const c: f64 = b;
    const d: f128 = c;
    try expect(d == a);
}

// test