feat: add missing tests/functionality

src/game.zig

@@ -23,15 +23,21 @@ const Vec2 = @Vector(2, i32);
 const State = enum {
     running,
     lost,
-    won,
 };
 
 const Game = struct {
     playFieldSize: Vec2,
-    food: Vec2,
     direction: Direction,
     body: std.ArrayList(Vec2),
     state: State,
+    rng: std.Random.DefaultPrng,
+
+    food: Vec2,
+    grow: bool,
+
+    pub fn score(self: Game) usize {
+        return self.body.items.len;
+    }
 
     pub fn createWithSize(allocator: std.mem.Allocator, bodySize: u8) !Game {
         var body = try std.ArrayList(Vec2).initCapacity(allocator, 1000);
@@ -42,12 +48,17 @@ const Game = struct {
             try body.append(Vec2{ startPos - index, 10 });
         }
 
+        const seed: u64 = @intCast(std.time.nanoTimestamp());
+        const prng = std.Random.DefaultPrng.init(seed);
+
         return Game{
             .playFieldSize = Vec2{ 20, 20 },
-            .food = Vec2{ 2, 5 },
+            .food = Vec2{ 11, 13 },
             .direction = Direction.right,
             .body = body,
             .state = State.running,
+            .rng = prng,
+            .grow = false,
         };
     }
 
@@ -95,7 +106,33 @@ const Game = struct {
         }
 
         try self.body.insert(0, newHead);
-        _ = self.body.pop();
+        if (self.grow) {
+            self.grow = false;
+        } else {
+            _ = self.body.pop();
+        }
+
+        if (std.meta.eql(newHead, self.food)) {
+            // TODO: randomize and check for collisions
+            self.food = self.getEmptySpace();
+            self.grow = true;
+        }
+    }
+
+    fn getEmptySpace(self: *Game) Vec2 {
+        outer: while (true) {
+            const x = self.rng.random().intRangeLessThan(i32, 0, self.playFieldSize[0]);
+            const y = self.rng.random().intRangeLessThan(i32, 0, self.playFieldSize[1]);
+
+            const potentialResult = Vec2{ x, y };
+            for (self.body.items) |pos| {
+                if (std.meta.eql(pos, potentialResult)) {
+                    continue :outer;
+                }
+            }
+
+            return potentialResult;
+        }
     }
 };
 
@@ -174,8 +211,26 @@ test "should loose if touching tail" {
     try testing.expectEqual(State.lost, game.state);
 }
 
-test "should grow if eating food" {}
-test "should win if no space is left" {}
-test "should tick if running" {}
-test "should fail tick if lost" {}
-test "should fail tick if won" {}
+test "should grow and spawn new food on ate food" {
+    const allocator = testing.allocator;
+
+    var game = try Game.create(allocator);
+    defer game.deinit();
+
+    try testing.expect(std.meta.eql(game.food, Vec2{ 11, 13 }));
+
+    try game.tick();
+    game.setDirection(Direction.down);
+    try game.tick();
+    try game.tick();
+    try game.tick();
+
+    const expected = [_]Vec2{ Vec2{ 11, 13 }, Vec2{ 11, 12 }, Vec2{ 11, 11 } };
+    try testing.expectEqualSlices(Vec2, &expected, game.body.items);
+    try testing.expect(!std.meta.eql(game.food, Vec2{ 11, 13 }));
+
+    try game.tick();
+
+    const expected2 = [_]Vec2{ Vec2{ 11, 14 }, Vec2{ 11, 13 }, Vec2{ 11, 12 }, Vec2{ 11, 11 } };
+    try testing.expectEqualSlices(Vec2, &expected2, game.body.items);
+}