core/tests/snapshot.rs

@@ -3,7 +3,7 @@ use grovewright_core::command::Command;
 use grovewright_core::hash::fnv1a64;
 use grovewright_core::map::{Map, Pos, Terrain};
 use grovewright_core::mapgen::outcrop_origin;
-use grovewright_core::player::{Player, PlayerId, MAX_ONLINE_PLAYERS};
+use grovewright_core::player::{Player, PlayerId, MAX_KNOWN_PLAYERS, MAX_ONLINE_PLAYERS};
 use grovewright_core::snapshot::{SnapshotError, MAX_RESTORABLE_TICK, SNAPSHOT_VERSION};
 use grovewright_core::world::{Event, World, DIG_COOLDOWN_TICKS};
 
@@ -256,3 +256,43 @@ fn states_right_at_the_limits_are_accepted() {
     let bytes = snapshot_of(1, MAX_RESTORABLE_TICK, &map, &players);
     assert!(World::from_snapshot(&bytes).is_ok());
 }
+
+/// A world that knows `MAX_KNOWN_PLAYERS` players, built through commands.
+/// They join in groups of `MAX_ONLINE_PLAYERS`, and each group but the last
+/// leaves before the next one joins, so only the last group is online.
+fn world_with_a_full_roster() -> World {
+    let mut world = World::new(7);
+    let groups = MAX_KNOWN_PLAYERS / MAX_ONLINE_PLAYERS;
+    for group in 0..groups {
+        let first = group * MAX_ONLINE_PLAYERS;
+        for index in first..first + MAX_ONLINE_PLAYERS {
+            world.step(&[Command::Join {
+                key: [index as u8; 16],
+                name: format!("P{index}"),
+            }]);
+        }
+        if group + 1 < groups {
+            for index in first..first + MAX_ONLINE_PLAYERS {
+                world.step(&[Command::Leave {
+                    player: PlayerId(index as u8),
+                }]);
+            }
+        }
+    }
+    world
+}
+
+#[test]
+fn a_full_roster_with_most_players_offline_is_accepted() {
+    let world = world_with_a_full_roster();
+    assert_eq!(world.players().len(), MAX_KNOWN_PLAYERS);
+    let online = world.players().iter().filter(|player| player.online);
+    assert_eq!(online.count(), MAX_ONLINE_PLAYERS);
+
+    let restored = World::from_snapshot(&world.to_snapshot()).unwrap();
+    assert_eq!(restored, world);
+
+    let loaded = World::load(&world.to_snapshot()).unwrap();
+    assert_eq!(loaded.players().len(), MAX_KNOWN_PLAYERS);
+    assert!(loaded.players().iter().all(|player| !player.online));
+}