You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: decoder_tests.rs
    path of file: ./repos/phaser/phaser/vendor/base64/src/read
    
    the code of the file until where you have to start completion: use std::io::{self, Read};

use rand::{Rng, RngCore};
use std::{cmp, iter};

use super::decoder::{DecoderReader, BUF_SIZE};
use crate::encode::encode_config_buf;
use crate::tests::random_config;
use crate::{decode_config_buf, DecodeError, STANDARD};

#[test]
fn simple() {
    let tests: &[(&[u8], &[u8])] = &[
        (&b"0"[..], &b"MA=="[..]),
        (b"01", b"MDE="),
        (b"012", b"MDEy"),
        (b"0123", b"MDEyMw=="),
        (b"01234", b"MDEyMzQ="),
        (b"012345", b"MDEyMzQ1"),
        (b"0123456", b"MDEyMzQ1Ng=="),
        (b"01234567", b"MDEyMzQ1Njc="),
        (b"012345678", b"MDEyMzQ1Njc4"),
        (b"0123456789", b"MDEyMzQ1Njc4OQ=="),
    ][..];

    for (text_expected, base64data) in tests.iter() {
        // Read n bytes at a time.
        for n in 1..base64data.len() + 1 {
            let mut wrapped_reader = io::Cursor::new(bas
    
fn handles_short_read_from_delegate() {
    let mut rng = rand::thread_rng();
    let mut bytes = Vec::new();
    let mut b64 = String::new();
    let mut decoded = Vec::new();

    for _ in 0..10_000 {
        bytes.clear();
        b64.clear();
        decoded.clear();

        let size = rng.gen_range(0, 10 * BUF_SIZE);
        bytes.extend(iter::repeat(0).take(size));
        bytes.truncate(size);
        rng.fill_bytes(&mut bytes[..size]);
        assert_eq!(size, bytes.len());

        let config = random_config(&mut rng);
        encode_config_buf(&bytes[..], config, &mut b64);

        let mut wrapped_reader = io::Cursor::new(b64.as_bytes());
        let mut short_reader = RandomShortRead {
            delegate: &mut wrapped_reader,
            rng: &mut rng,
        };

        let mut decoder = DecoderReader::new(&mut short_reader, config);

        let decoded_len = decoder.read_to_end(&mut decoded).unwrap();
        assert_eq!(size, decoded_len);
        assert_eq!(&bytes[..], &decoded[..]);
    }
}