mc_protocol 2.1.1

Rust implementation of Minecraft Java Edition protocol primitives: serialization, packet framing, encryption, and compression
Documentation 
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//! Tests for zlib packet compression.

use mc_protocol::compression::{compress_zlib, compress_zlib_level, decompress_zlib};
use mc_protocol::packet::UncompressedPacket;

// ---------------------------------------------------------------------------
// compress_zlib / decompress_zlib
// ---------------------------------------------------------------------------

#[test]
fn compress_then_decompress_round_trip() {
    let original = b"Hello, Minecraft Protocol!";
    let compressed = compress_zlib(original).unwrap();
    let decompressed = decompress_zlib(&compressed).unwrap();
    assert_eq!(decompressed, original);
}

#[test]
fn compress_empty_input() {
    let compressed = compress_zlib(&[]).unwrap();
    let decompressed = decompress_zlib(&compressed).unwrap();
    assert_eq!(decompressed, &[] as &[u8]);
}

#[test]
fn compressed_data_smaller_for_repetitive_input() {
    let data: Vec<u8> = vec![0xAA; 1000];
    let compressed = compress_zlib(&data).unwrap();
    assert!(
        compressed.len() < data.len(),
        "Compressed size {} should be smaller than original {}",
        compressed.len(),
        data.len()
    );
}

#[test]
fn compress_level_0_no_compression() {
    let data = b"Some test data";
    let no_compress = compress_zlib_level(data, 0).unwrap();
    let default_compress = compress_zlib(data).unwrap();
    // Both should decompress to the same thing
    assert_eq!(decompress_zlib(&no_compress).unwrap(), data);
    assert_eq!(decompress_zlib(&default_compress).unwrap(), data);
}

#[test]
fn decompress_invalid_data_returns_error() {
    let garbage = b"this is not valid zlib data at all xyz";
    let result = decompress_zlib(garbage);
    assert!(result.is_err(), "Expected error for invalid zlib data");
}

// ---------------------------------------------------------------------------
// Packet-level compression
// ---------------------------------------------------------------------------

#[test]
fn packet_below_threshold_not_compressed() {
    let up = UncompressedPacket::new(0x00, vec![0x01, 0x02, 0x03]);
    let threshold = Some(256); // payload is well below 256 bytes

    let raw = up.to_raw_packet_compressed(threshold).unwrap();

    // Decompress and verify we get back the same packet
    let decoded = raw.uncompress(threshold).unwrap();
    assert_eq!(decoded.packet_id, 0x00);
    assert_eq!(decoded.payload, &[0x01, 0x02, 0x03]);
}

#[test]
fn packet_above_threshold_is_compressed() {
    // Build a payload large enough to exceed the threshold
    let payload = vec![0u8; 512];
    let up = UncompressedPacket::new(0x26, payload.clone());
    let threshold = Some(256);

    let raw = up.to_raw_packet_compressed(threshold).unwrap();
    let decoded = raw.uncompress(threshold).unwrap();

    assert_eq!(decoded.packet_id, 0x26);
    assert_eq!(decoded.payload, payload);
}

#[test]
fn packet_no_threshold_no_compression() {
    let up = UncompressedPacket::new(0x10, vec![1, 2, 3, 4, 5]);
    let raw = up.to_raw_packet_compressed(None).unwrap();
    let decoded = raw.uncompress(None).unwrap();

    assert_eq!(decoded.packet_id, 0x10);
    assert_eq!(decoded.payload, &[1, 2, 3, 4, 5]);
}

#[test]
fn large_packet_round_trip_preserves_exact_content() {
    // Simulate a chunk data packet with lots of bytes
    let payload: Vec<u8> = (0..2000).map(|i| (i % 256) as u8).collect();
    let up = UncompressedPacket::new(0x25, payload.clone());
    let threshold = Some(256);

    let raw = up.to_raw_packet_compressed(threshold).unwrap();
    let decoded = raw.uncompress(threshold).unwrap();

    assert_eq!(decoded.payload, payload);
    assert_eq!(decoded.payload.len(), 2000);
}