Grovewright/core/tests/golden.rs

//! Pinned values for everything that must not change unnoticed.
//!
//! Most other tests compare two computations inside the same build, so a
//! change that affects both sides alike stays green. This file compares
//! against values recorded once. If one of them fails, rules or encodings
//! changed, on purpose or by accident. If saves or recordings are affected,
//! raise the version constant named in the failure message, then update the
//! value here deliberately.

use grovewright_core::codec::Writer;
use grovewright_core::command::Command;
use grovewright_core::hash::fnv1a64;
use grovewright_core::map::{Map, Pos, Terrain, Tile};
use grovewright_core::mapgen::outcrop_origin;
use grovewright_core::player::PlayerId;
use grovewright_core::replay::Recording;
use grovewright_core::world::World;

const SEED: u64 = 2026;

/// The commands of a session of 60 ticks. It is built from literal values
/// and the outcrop origin of the map, not from constants such as
/// `DIG_COOLDOWN_TICKS`, so that changing a rule changes the result and not
/// the script.
///
/// Never change or extend this script. To pin more, add a new script and a
/// new pinned value instead.
fn frozen_script(world: &World) -> Vec<Vec<Command>> {
    let origin = outcrop_origin(world.map());
    let right_of_origin = Pos::new(origin.x + 1, origin.y);
    // Pairs of (tick, command). Commands of the same tick are applied in the
    // order listed here.
    let scripted = [
        // Two players join in the same tick.
        (
            0,
            Command::Join {
                key: [1; 16],
                name: "Ada".to_owned(),
            },
        ),
        (
            0,
            Command::Join {
                key: [2; 16],
                name: "Grace".to_owned(),
            },
        ),
        // Player 0 hits the outcrop origin three times, five ticks apart.
        // The third hit breaks the rock and gives a stone.
        (
            2,
            Command::Dig {
                player: PlayerId(0),
                pos: origin,
            },
        ),
        (
            7,
            Command::Dig {
                player: PlayerId(0),
                pos: origin,
            },
        ),
        (
            12,
            Command::Dig {
                player: PlayerId(0),
                pos: origin,
            },
        ),
        // Player 1 hits the tile to the right of the origin once.
        (
            20,
            Command::Dig {
                player: PlayerId(1),
                pos: right_of_origin,
            },
        ),
        // Player 1 leaves and returns with a name of 40 bytes, which the
        // world shortens to 32.
        (
            30,
            Command::Leave {
                player: PlayerId(1),
            },
        ),
        (
            40,
            Command::Join {
                key: [2; 16],
                name: "ä".repeat(20),
            },
        ),
    ];
    let mut ticks = vec![Vec::new(); 60];
    for (tick, command) in scripted {
        ticks[tick].push(command);
    }
    ticks
}

/// The commands of a second session of 30 ticks that ends with one player
/// offline, so that the encoding of offline players is pinned as well.
///
/// Never change or extend this script either.
fn frozen_offline_script(world: &World) -> Vec<Vec<Command>> {
    let origin = outcrop_origin(world.map());
    let scripted = [
        (
            0,
            Command::Join {
                key: [7; 16],
                name: "Linus".to_owned(),
            },
        ),
        (
            1,
            Command::Join {
                key: [8; 16],
                name: "Margaret".to_owned(),
            },
        ),
        (
            3,
            Command::Dig {
                player: PlayerId(1),
                pos: origin,
            },
        ),
        (
            10,
            Command::Leave {
                player: PlayerId(0),
            },
        ),
    ];
    let mut ticks = vec![Vec::new(); 30];
    for (tick, command) in scripted {
        ticks[tick].push(command);
    }
    ticks
}

/// Covers the map generator, the map encoding and the snapshot header and
/// checksum.
#[test]
fn the_starting_snapshot_is_unchanged() {
    let actual = fnv1a64(&World::new(SEED).to_snapshot());
    assert_eq!(
        actual, 0x6812_937b_f2b2_19ae,
        "the starting world or the snapshot format changed; if saves are \
         affected, raise SNAPSHOT_VERSION in core/src/snapshot.rs; then \
         update this value"
    );
}

/// Covers the rules of joining, leaving and digging, the shortening of names
/// and the encoding of players.
#[test]
fn the_frozen_session_ends_in_the_same_state() {
    let mut world = World::new(SEED);
    for commands in frozen_script(&world) {
        world.step(&commands);
    }
    assert_eq!(
        world.state_hash(),
        0xc304_43df_fc74_dcfc,
        "the rules or the snapshot format changed; old recordings no longer \
         verify; if saves are affected, raise SNAPSHOT_VERSION in \
         core/src/snapshot.rs; then update this value"
    );
}

/// Covers the encoding of a player who is offline.
#[test]
fn the_frozen_offline_session_ends_in_the_same_state() {
    let mut world = World::new(SEED);
    for commands in frozen_offline_script(&world) {
        world.step(&commands);
    }
    assert_eq!(
        world.state_hash(),
        0x904f_10e1_7c52_8be4,
        "the rules or the snapshot format changed; old recordings no longer \
         verify; if saves are affected, raise SNAPSHOT_VERSION in \
         core/src/snapshot.rs; then update this value"
    );
}

/// Covers the recording header and layout and the wire format of commands.
#[test]
fn the_recording_format_is_unchanged() {
    let mut world = World::new(SEED);
    let mut recording = Recording::start(&world);
    for commands in frozen_script(&world) {
        recording.push_tick(&commands);
        world.step(&commands);
    }
    assert_eq!(
        fnv1a64(&recording.to_bytes(&world)),
        0x1c24_8cc7_6bc8_846a,
        "the recording or command format changed; if other tests in this \
         file fail as well, deal with those first, because a recording \
         contains a snapshot and an end state; otherwise raise \
         RECORDING_VERSION in core/src/replay.rs; then update this value"
    );
}

/// Covers the byte layout of a map: width before height, little endian,
/// terrain numbers and damage. The map is not square, so a swap of width
/// and height shows.
#[test]
fn the_map_encoding_is_unchanged() {
    let mut map = Map::filled(3, 2, Terrain::Ground);
    map.set(Pos::new(1, 0), Tile::new(Terrain::Bedrock));
    map.set(Pos::new(0, 1), Tile::new(Terrain::HardRock));
    map.set(
        Pos::new(2, 1),
        Tile {
            terrain: Terrain::SoftRock,
            damage: 1,
        },
    );
    let mut w = Writer::new();
    map.encode(&mut w);
    assert_eq!(
        w.into_bytes(),
        vec![
            3, 0, 0, 0, // width
            2, 0, 0, 0, // height
            0, 0, 3, 0, 0, 0, // row 0: ground, bedrock, ground
            2, 0, 0, 0, 1, 1, // row 1: hard rock, ground, soft rock hit once
        ],
        "the map encoding changed; raise SNAPSHOT_VERSION in \
         core/src/snapshot.rs; then update these bytes"
    );
}