refactor: fix boop placement

src/samples/boop/index.ts

@@ -4,18 +4,26 @@ const BOARD_SIZE = 6;
 const MAX_PIECES_PER_PLAYER = 8;
 const WIN_LENGTH = 3;
 
-const DIRECTIONS = [
-    [-1, -1], [-1, 0], [-1, 1],
-    [0, -1],           [0, 1],
-    [1, -1],  [1, 0],  [1, 1],
-];
-
 export type PlayerType = 'white' | 'black';
 export type PieceType = 'kitten' | 'cat';
 export type WinnerType = PlayerType | 'draw' | null;
 
 type BoopPart = Part & { player: PlayerType; pieceType: PieceType };
 
+type PieceSupply = { supply: number; placed: number };
+
+type PlayerSupply = {
+    kitten: PieceSupply;
+    cat: PieceSupply;
+};
+
+function createPlayerSupply(): PlayerSupply {
+    return {
+        kitten: { supply: MAX_PIECES_PER_PLAYER, placed: 0 },
+        cat: { supply: 0, placed: 0 },
+    };
+}
+
 export function createInitialState() {
     return {
         board: new RegionEntity('board', {
@@ -26,13 +34,12 @@ export function createInitialState() {
             ],
             children: [],
         }),
-        parts: [] as Entity<BoopPart>[],
         currentPlayer: 'white' as PlayerType,
         winner: null as WinnerType,
-        whiteKittensInSupply: MAX_PIECES_PER_PLAYER,
+        players: {
-        blackKittensInSupply: MAX_PIECES_PER_PLAYER,
+            white: createPlayerSupply(),
-        whiteCatsInSupply: 0,
+            black: createPlayerSupply(),
-        blackCatsInSupply: 0,
+        },
     };
 }
 export type BoopState = ReturnType<typeof createInitialState>;
@@ -65,23 +72,23 @@ registration.add('turn <player>', async function(cmd) {
 
     while (retries < maxRetries) {
         retries++;
-        const playCmd = await this.prompt('play <player> <row:number> <col:number>');
+        const playCmd = await this.prompt('play <player> <row:number> <col:number> [type:string]');
-        const [player, row, col] = playCmd.params as [PlayerType, number, number];
+        const [player, row, col, type] = playCmd.params as [PlayerType, number, number, PieceType?];
+        const pieceType = type === 'cat' ? 'cat' : 'kitten';
 
         if (player !== turnPlayer) continue;
         if (!isValidMove(row, col)) continue;
         if (isCellOccupied(this.context, row, col)) continue;
 
-        const state = this.context.value;
+        const supply = this.context.value.players[player][pieceType].supply;
-        const kittensInSupply = player === 'white' ? state.whiteKittensInSupply : state.blackKittensInSupply;
+        if (supply <= 0) continue;
-        if (kittensInSupply <= 0) continue;
 
-        placeKitten(this.context, row, col, turnPlayer);
+        placePiece(this.context, row, col, turnPlayer, pieceType);
-        applyBoops(this.context, row, col, 'kitten');
+        applyBoops(this.context, row, col, pieceType);
 
-        const graduatedRows = checkGraduation(this.context, turnPlayer);
+        const graduatedLines = checkGraduation(this.context, turnPlayer);
-        if (graduatedRows.length > 0) {
+        if (graduatedLines.length > 0) {
-            processGraduation(this.context, turnPlayer, graduatedRows);
+            processGraduation(this.context, turnPlayer, graduatedLines);
         }
 
         const winner = checkWinner(this.context);
@@ -111,21 +118,21 @@ export function getPartAt(host: Entity<BoopState>, row: number, col: number): En
     return (board.partsMap.value[`${row},${col}`] as Entity<BoopPart> | undefined) || null;
 }
 
-export function placeKitten(host: Entity<BoopState>, row: number, col: number, player: PlayerType) {
+export function placePiece(host: Entity<BoopState>, row: number, col: number, player: PlayerType, pieceType: PieceType) {
     const board = getBoardRegion(host);
-    const moveNumber = host.value.parts.length + 1;
+    const count = host.value.players[player][pieceType].placed + 1;
+
     const piece: BoopPart = {
-        id: `piece-${player}-${moveNumber}`,
+        id: `${player}-${pieceType}-${count}`,
         region: board,
         position: [row, col],
         player,
-        pieceType: 'kitten',
+        pieceType,
     };
-    host.produce(state => {
+    host.produce(s => {
         const e = entity(piece.id, piece);
-        state.parts.push(e);
+        s.players[player][pieceType].supply--;
-        if (player === 'white') state.whiteKittensInSupply--;
+        s.players[player][pieceType].placed++;
-        else state.blackKittensInSupply--;
         board.produce(draft => {
             draft.children.push(e);
         });
@@ -162,11 +169,11 @@ export function applyBoops(host: Entity<BoopState>, placedRow: number, placedCol
         const newCol = c + dc;
 
         if (newRow < 0 || newRow >= BOARD_SIZE || newCol < 0 || newCol >= BOARD_SIZE) {
+            const pt = part.value.pieceType;
+            const pl = part.value.player;
             removePieceFromBoard(host, part);
-            const player = part.value.player;
             host.produce(state => {
-                if (player === 'white') state.whiteKittensInSupply++;
+                state.players[pl][pt].supply++;
-                else state.blackKittensInSupply++;
             });
             continue;
         }
@@ -181,17 +188,22 @@ export function applyBoops(host: Entity<BoopState>, placedRow: number, placedCol
 
 export function removePieceFromBoard(host: Entity<BoopState>, part: Entity<BoopPart>) {
     const board = getBoardRegion(host);
-    host.produce(state => {
-        state.parts = state.parts.filter(p => p.id !== part.id);
     board.produce(draft => {
         draft.children = draft.children.filter(p => p.id !== part.id);
     });
-    });
 }
 
 export function checkGraduation(host: Entity<BoopState>, player: PlayerType): number[][][] {
-    const parts = host.value.parts.filter(p => p.value.player === player && p.value.pieceType === 'kitten');
+    const board = getBoardRegion(host);
-    const positions = parts.map(p => p.value.position);
+    const partsMap = board.partsMap.value;
+    const positions: number[][] = [];
+
+    for (const key in partsMap) {
+        const part = partsMap[key] as Entity<BoopPart>;
+        if (part.value.player === player && part.value.pieceType === 'kitten') {
+            positions.push(part.value.position);
+        }
+    }
 
     const winningLines: number[][][] = [];
 
@@ -271,25 +283,30 @@ export function processGraduation(host: Entity<BoopState>, player: PlayerType, l
 
     const count = partsToRemove.length;
     host.produce(state => {
-        const catsInSupply = player === 'white' ? state.whiteCatsInSupply : state.blackCatsInSupply;
+        state.players[player].cat.supply += count;
-        if (player === 'white') state.whiteCatsInSupply = catsInSupply + count;
-        else state.blackCatsInSupply = catsInSupply + count;
     });
 }
 
 export function checkWinner(host: Entity<BoopState>): WinnerType {
-    for (const player of ['white', 'black'] as PlayerType[]) {
+    const board = getBoardRegion(host);
-        const parts = host.value.parts.filter(p => p.value.player === player && p.value.pieceType === 'cat');
+    const partsMap = board.partsMap.value;
-        const positions = parts.map(p => p.value.position);
 
+    for (const player of ['white', 'black'] as PlayerType[]) {
+        const positions: number[][] = [];
+        for (const key in partsMap) {
+            const part = partsMap[key] as Entity<BoopPart>;
+            if (part.value.player === player && part.value.pieceType === 'cat') {
+                positions.push(part.value.position);
+            }
+        }
         if (hasWinningLine(positions)) return player;
     }
 
-    const totalParts = host.value.parts.length;
+    const state = host.value;
-    const whiteParts = host.value.parts.filter(p => p.value.player === 'white').length;
+    const whiteTotal = MAX_PIECES_PER_PLAYER - state.players.white.kitten.supply + state.players.white.cat.supply;
-    const blackParts = host.value.parts.filter(p => p.value.player === 'black').length;
+    const blackTotal = MAX_PIECES_PER_PLAYER - state.players.black.kitten.supply + state.players.black.cat.supply;
 
-    if (whiteParts >= MAX_PIECES_PER_PLAYER && blackParts >= MAX_PIECES_PER_PLAYER) {
+    if (whiteTotal >= MAX_PIECES_PER_PLAYER && blackTotal >= MAX_PIECES_PER_PLAYER) {
         return 'draw';
     }
 

tests/samples/boop.test.ts

@@ -4,7 +4,7 @@ import {
     checkWinner,
     isCellOccupied,
     getPartAt,
-    placeKitten,
+    placePiece,
     applyBoops,
     checkGraduation,
     processGraduation,
@@ -35,6 +35,10 @@ function waitForPrompt(ctx: ReturnType<typeof createTestContext>['ctx']): Promis
     });
 }
 
+function getParts(state: Entity<BoopState>) {
+    return state.value.board.value.children;
+}
+
 describe('Boop - helper functions', () => {
     describe('isCellOccupied', () => {
         it('should return false for empty cell', () => {
@@ -47,7 +51,7 @@ describe('Boop - helper functions', () => {
         it('should return true for occupied cell', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
-            placeKitten(state, 3, 3, 'white');
+            placePiece(state, 3, 3, 'white', 'kitten');
 
             expect(isCellOccupied(state, 3, 3)).toBe(true);
         });
@@ -55,7 +59,7 @@ describe('Boop - helper functions', () => {
         it('should return false for different cell', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
-            placeKitten(state, 0, 0, 'white');
+            placePiece(state, 0, 0, 'white', 'kitten');
 
             expect(isCellOccupied(state, 1, 1)).toBe(false);
         });
@@ -72,7 +76,7 @@ describe('Boop - helper functions', () => {
         it('should return the part at occupied cell', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
-            placeKitten(state, 2, 2, 'black');
+            placePiece(state, 2, 2, 'black', 'kitten');
 
             const part = getPartAt(state, 2, 2);
             expect(part).not.toBeNull();
@@ -83,35 +87,72 @@ describe('Boop - helper functions', () => {
         });
     });
 
-    describe('placeKitten', () => {
+    describe('placePiece', () => {
         it('should add a kitten to the board', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
-            placeKitten(state, 2, 3, 'white');
+            placePiece(state, 2, 3, 'white', 'kitten');
 
-            expect(state.value.parts.length).toBe(1);
+            const parts = getParts(state);
-            expect(state.value.parts[0].value.position).toEqual([2, 3]);
+            expect(parts.length).toBe(1);
-            expect(state.value.parts[0].value.player).toBe('white');
+            expect(parts[0].value.position).toEqual([2, 3]);
-            expect(state.value.parts[0].value.pieceType).toBe('kitten');
+            expect(parts[0].value.player).toBe('white');
+            expect(parts[0].value.pieceType).toBe('kitten');
+        });
+
+        it('should name piece white-kitten-1', () => {
+            const { ctx } = createTestContext();
+            const state = getState(ctx);
+            placePiece(state, 0, 0, 'white', 'kitten');
+
+            expect(getParts(state)[0].id).toBe('white-kitten-1');
+        });
+
+        it('should name piece white-kitten-2 for second white kitten', () => {
+            const { ctx } = createTestContext();
+            const state = getState(ctx);
+            placePiece(state, 0, 0, 'white', 'kitten');
+            placePiece(state, 0, 1, 'white', 'kitten');
+
+            expect(getParts(state)[1].id).toBe('white-kitten-2');
+        });
+
+        it('should name piece white-cat-1', () => {
+            const { ctx } = createTestContext();
+            const state = getState(ctx);
+            placePiece(state, 0, 0, 'white', 'cat');
+
+            expect(getParts(state)[0].id).toBe('white-cat-1');
         });
 
         it('should decrement the correct player kitten supply', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 0, 0, 'white');
+            placePiece(state, 0, 0, 'white', 'kitten');
-            expect(state.value.whiteKittensInSupply).toBe(7);
+            expect(state.value.players.white.kitten.supply).toBe(7);
-            expect(state.value.blackKittensInSupply).toBe(8);
+            expect(state.value.players.black.kitten.supply).toBe(8);
 
-            placeKitten(state, 0, 1, 'black');
+            placePiece(state, 0, 1, 'black', 'kitten');
-            expect(state.value.whiteKittensInSupply).toBe(7);
+            expect(state.value.players.white.kitten.supply).toBe(7);
-            expect(state.value.blackKittensInSupply).toBe(7);
+            expect(state.value.players.black.kitten.supply).toBe(7);
+        });
+
+        it('should decrement the correct player cat supply', () => {
+            const { ctx } = createTestContext();
+            const state = getState(ctx);
+            state.produce(s => {
+                s.players.white.cat.supply = 3;
+            });
+
+            placePiece(state, 0, 0, 'white', 'cat');
+            expect(state.value.players.white.cat.supply).toBe(2);
         });
 
         it('should add piece to board region children', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
-            placeKitten(state, 1, 1, 'white');
+            placePiece(state, 1, 1, 'white', 'kitten');
 
             const board = getBoardRegion(state);
             expect(board.value.children.length).toBe(1);
@@ -120,10 +161,10 @@ describe('Boop - helper functions', () => {
         it('should generate unique IDs for pieces', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
-            placeKitten(state, 0, 0, 'white');
+            placePiece(state, 0, 0, 'white', 'kitten');
-            placeKitten(state, 0, 1, 'black');
+            placePiece(state, 0, 1, 'black', 'kitten');
 
-            const ids = state.value.parts.map(p => p.id);
+            const ids = getParts(state).map(p => p.id);
             expect(new Set(ids).size).toBe(2);
         });
     });
@@ -133,22 +174,23 @@ describe('Boop - helper functions', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 3, 3, 'black');
+            placePiece(state, 3, 3, 'black', 'kitten');
-            placeKitten(state, 2, 2, 'white');
+            placePiece(state, 2, 2, 'white', 'kitten');
 
-            expect(state.value.parts[1].value.position).toEqual([2, 2]);
+            const whitePart = getParts(state)[1];
+            expect(whitePart.value.position).toEqual([2, 2]);
 
             applyBoops(state, 3, 3, 'kitten');
 
-            expect(state.value.parts[1].value.position).toEqual([1, 1]);
+            expect(whitePart.value.position).toEqual([1, 1]);
         });
 
         it('should not boop a cat when a kitten is placed', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 3, 3, 'black');
+            placePiece(state, 3, 3, 'black', 'kitten');
-            const whitePart = state.value.parts[0];
+            const whitePart = getParts(state)[0];
             whitePart.produce(p => {
                 p.pieceType = 'cat';
             });
@@ -162,27 +204,27 @@ describe('Boop - helper functions', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 0, 0, 'white');
+            placePiece(state, 0, 0, 'white', 'kitten');
-            placeKitten(state, 1, 1, 'black');
+            placePiece(state, 1, 1, 'black', 'kitten');
 
             applyBoops(state, 1, 1, 'kitten');
 
-            expect(state.value.parts.length).toBe(1);
+            expect(getParts(state).length).toBe(1);
-            expect(state.value.parts[0].value.player).toBe('black');
+            expect(getParts(state)[0].value.player).toBe('black');
-            expect(state.value.whiteKittensInSupply).toBe(8);
+            expect(state.value.players.white.kitten.supply).toBe(8);
         });
 
         it('should not boop piece if target cell is occupied', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 1, 1, 'white');
+            placePiece(state, 1, 1, 'white', 'kitten');
-            placeKitten(state, 2, 1, 'black');
+            placePiece(state, 2, 1, 'black', 'kitten');
-            placeKitten(state, 0, 1, 'black');
+            placePiece(state, 0, 1, 'black', 'kitten');
 
             applyBoops(state, 0, 1, 'kitten');
 
-            const whitePart = state.value.parts.find(p => p.value.player === 'white');
+            const whitePart = getParts(state).find(p => p.value.player === 'white');
             expect(whitePart).toBeDefined();
             if (whitePart) {
                 expect(whitePart.value.position).toEqual([1, 1]);
@@ -193,38 +235,37 @@ describe('Boop - helper functions', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 3, 3, 'white');
+            placePiece(state, 3, 3, 'white', 'kitten');
-            placeKitten(state, 2, 2, 'black');
+            placePiece(state, 2, 2, 'black', 'kitten');
-            placeKitten(state, 2, 3, 'black');
+            placePiece(state, 2, 3, 'black', 'kitten');
 
             applyBoops(state, 3, 3, 'kitten');
 
-            expect(state.value.parts[1].value.position).toEqual([1, 1]);
+            expect(getParts(state)[1].value.position).toEqual([1, 1]);
-            expect(state.value.parts[2].value.position).toEqual([1, 3]);
+            expect(getParts(state)[2].value.position).toEqual([1, 3]);
         });
 
         it('should not boop the placed piece itself', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 3, 3, 'white');
+            placePiece(state, 3, 3, 'white', 'kitten');
 
             applyBoops(state, 3, 3, 'kitten');
 
-            expect(state.value.parts[0].value.position).toEqual([3, 3]);
+            expect(getParts(state)[0].value.position).toEqual([3, 3]);
         });
     });
 
     describe('removePieceFromBoard', () => {
-        it('should remove piece from parts and board children', () => {
+        it('should remove piece from board children', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
-            placeKitten(state, 2, 2, 'white');
+            placePiece(state, 2, 2, 'white', 'kitten');
-            const part = state.value.parts[0];
+            const part = getParts(state)[0];
 
             removePieceFromBoard(state, part);
 
-            expect(state.value.parts.length).toBe(0);
             const board = getBoardRegion(state);
             expect(board.value.children.length).toBe(0);
         });
@@ -235,8 +276,8 @@ describe('Boop - helper functions', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 0, 0, 'white');
+            placePiece(state, 0, 0, 'white', 'kitten');
-            placeKitten(state, 2, 2, 'white');
+            placePiece(state, 2, 2, 'white', 'kitten');
 
             const lines = checkGraduation(state, 'white');
             expect(lines.length).toBe(0);
@@ -246,9 +287,9 @@ describe('Boop - helper functions', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 1, 0, 'white');
+            placePiece(state, 1, 0, 'white', 'kitten');
-            placeKitten(state, 1, 1, 'white');
+            placePiece(state, 1, 1, 'white', 'kitten');
-            placeKitten(state, 1, 2, 'white');
+            placePiece(state, 1, 2, 'white', 'kitten');
 
             const lines = checkGraduation(state, 'white');
             expect(lines.length).toBe(1);
@@ -259,9 +300,9 @@ describe('Boop - helper functions', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 0, 2, 'white');
+            placePiece(state, 0, 2, 'white', 'kitten');
-            placeKitten(state, 1, 2, 'white');
+            placePiece(state, 1, 2, 'white', 'kitten');
-            placeKitten(state, 2, 2, 'white');
+            placePiece(state, 2, 2, 'white', 'kitten');
 
             const lines = checkGraduation(state, 'white');
             expect(lines.length).toBe(1);
@@ -272,9 +313,9 @@ describe('Boop - helper functions', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 0, 0, 'white');
+            placePiece(state, 0, 0, 'white', 'kitten');
-            placeKitten(state, 1, 1, 'white');
+            placePiece(state, 1, 1, 'white', 'kitten');
-            placeKitten(state, 2, 2, 'white');
+            placePiece(state, 2, 2, 'white', 'kitten');
 
             const lines = checkGraduation(state, 'white');
             expect(lines.length).toBe(1);
@@ -285,9 +326,9 @@ describe('Boop - helper functions', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 2, 0, 'white');
+            placePiece(state, 2, 0, 'white', 'kitten');
-            placeKitten(state, 1, 1, 'white');
+            placePiece(state, 1, 1, 'white', 'kitten');
-            placeKitten(state, 0, 2, 'white');
+            placePiece(state, 0, 2, 'white', 'kitten');
 
             const lines = checkGraduation(state, 'white');
             expect(lines.length).toBe(1);
@@ -298,11 +339,11 @@ describe('Boop - helper functions', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 0, 0, 'white');
+            placePiece(state, 0, 0, 'white', 'kitten');
-            placeKitten(state, 0, 1, 'white');
+            placePiece(state, 0, 1, 'white', 'kitten');
-            placeKitten(state, 0, 2, 'white');
+            placePiece(state, 0, 2, 'white', 'kitten');
 
-            state.value.parts[1].produce(p => {
+            getParts(state)[1].produce(p => {
                 p.pieceType = 'cat';
             });
 
@@ -316,34 +357,34 @@ describe('Boop - helper functions', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 0, 0, 'white');
+            placePiece(state, 0, 0, 'white', 'kitten');
-            placeKitten(state, 0, 1, 'white');
+            placePiece(state, 0, 1, 'white', 'kitten');
-            placeKitten(state, 0, 2, 'white');
+            placePiece(state, 0, 2, 'white', 'kitten');
 
             const lines = checkGraduation(state, 'white');
             expect(lines.length).toBe(1);
 
             processGraduation(state, 'white', lines);
 
-            expect(state.value.parts.length).toBe(0);
+            expect(getParts(state).length).toBe(0);
-            expect(state.value.whiteCatsInSupply).toBe(3);
+            expect(state.value.players.white.cat.supply).toBe(3);
         });
 
         it('should only graduate pieces on the winning lines', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 0, 0, 'white');
+            placePiece(state, 0, 0, 'white', 'kitten');
-            placeKitten(state, 0, 1, 'white');
+            placePiece(state, 0, 1, 'white', 'kitten');
-            placeKitten(state, 0, 2, 'white');
+            placePiece(state, 0, 2, 'white', 'kitten');
-            placeKitten(state, 3, 3, 'white');
+            placePiece(state, 3, 3, 'white', 'kitten');
 
             const lines = checkGraduation(state, 'white');
             processGraduation(state, 'white', lines);
 
-            expect(state.value.parts.length).toBe(1);
+            expect(getParts(state).length).toBe(1);
-            expect(state.value.parts[0].value.position).toEqual([3, 3]);
+            expect(getParts(state)[0].value.position).toEqual([3, 3]);
-            expect(state.value.whiteCatsInSupply).toBe(3);
+            expect(state.value.players.white.cat.supply).toBe(3);
         });
     });
 
@@ -381,15 +422,9 @@ describe('Boop - helper functions', () => {
             const { ctx } = createTestContext();
             const state = getState(ctx);
 
-            placeKitten(state, 0, 0, 'white');
+            placePiece(state, 0, 0, 'white', 'cat');
-            placeKitten(state, 0, 1, 'white');
+            placePiece(state, 0, 1, 'white', 'cat');
-            placeKitten(state, 0, 2, 'white');
+            placePiece(state, 0, 2, 'white', 'cat');
-
-            state.value.parts.forEach(p => {
-                p.produce(part => {
-                    part.pieceType = 'cat';
-                });
-            });
 
             expect(checkWinner(state)).toBe('white');
         });
@@ -399,10 +434,10 @@ describe('Boop - helper functions', () => {
             const state = getState(ctx);
 
             for (let i = 0; i < 8; i++) {
-                placeKitten(state, i % 6, Math.floor(i / 6) + (i % 2), 'white');
+                placePiece(state, i % 6, Math.floor(i / 6) + (i % 2), 'white', 'kitten');
             }
             for (let i = 0; i < 8; i++) {
-                placeKitten(state, i % 6, Math.floor(i / 6) + 3 + (i % 2), 'black');
+                placePiece(state, i % 6, Math.floor(i / 6) + 3 + (i % 2), 'black', 'kitten');
             }
 
             const result = checkWinner(state);
@@ -450,8 +485,9 @@ describe('Boop - game flow', () => {
         const result = await runPromise;
         expect(result.success).toBe(true);
         if (result.success) expect(result.result.winner).toBeNull();
-        expect(ctx.state.value.parts.length).toBe(1);
+        expect(getParts(ctx.state).length).toBe(1);
-        expect(ctx.state.value.parts[0].value.position).toEqual([2, 2]);
+        expect(getParts(ctx.state)[0].value.position).toEqual([2, 2]);
+        expect(getParts(ctx.state)[0].id).toBe('white-kitten-1');
     });
 
     it('should reject move for wrong player and re-prompt', async () => {
@@ -477,7 +513,7 @@ describe('Boop - game flow', () => {
         const { ctx } = createTestContext();
         const state = getState(ctx);
 
-        placeKitten(state, 2, 2, 'black');
+        placePiece(state, 2, 2, 'black', 'kitten');
 
         const promptPromise = waitForPrompt(ctx);
         const runPromise = ctx.commands.run<{winner: WinnerType}>('turn white');
@@ -500,7 +536,7 @@ describe('Boop - game flow', () => {
         const state = getState(ctx);
 
         state.produce(s => {
-            s.whiteKittensInSupply = 0;
+            s.players.white.kitten.supply = 0;
         });
 
         const promptPromise = waitForPrompt(ctx);
@@ -528,7 +564,7 @@ describe('Boop - game flow', () => {
         prompt.resolve({ name: 'play', params: ['white', 3, 3], options: {}, flags: {} });
         let result = await runPromise;
         expect(result.success).toBe(true);
-        expect(state.value.parts.length).toBe(1);
+        expect(getParts(state).length).toBe(1);
 
         promptPromise = waitForPrompt(ctx);
         runPromise = ctx.commands.run<{winner: WinnerType}>('turn black');
@@ -536,29 +572,74 @@ describe('Boop - game flow', () => {
         prompt.resolve({ name: 'play', params: ['black', 2, 2], options: {}, flags: {} });
         result = await runPromise;
         expect(result.success).toBe(true);
-        expect(state.value.parts.length).toBe(2);
+        expect(getParts(state).length).toBe(2);
 
-        const whitePart = state.value.parts.find(p => p.value.player === 'white');
+        const whitePart = getParts(state).find(p => p.value.player === 'white');
         expect(whitePart).toBeDefined();
         if (whitePart) {
             expect(whitePart.value.position).not.toEqual([3, 3]);
         }
     });
 
-    it('should graduate kittens to cats and check for cat win', async () => {
+    it('should graduate kittens to cats and check for cat win', () => {
         const { ctx } = createTestContext();
         const state = getState(ctx);
 
-        placeKitten(state, 1, 0, 'white');
+        placePiece(state, 1, 0, 'white', 'kitten');
-        placeKitten(state, 1, 1, 'white');
+        placePiece(state, 1, 1, 'white', 'kitten');
-        placeKitten(state, 1, 2, 'white');
+        placePiece(state, 1, 2, 'white', 'kitten');
 
         const lines = checkGraduation(state, 'white');
         expect(lines.length).toBeGreaterThanOrEqual(1);
 
         processGraduation(state, 'white', lines);
 
-        expect(state.value.parts.length).toBe(0);
+        expect(getParts(state).length).toBe(0);
-        expect(state.value.whiteCatsInSupply).toBe(3);
+        expect(state.value.players.white.cat.supply).toBe(3);
+    });
+
+    it('should accept placing a cat via play command', async () => {
+        const { ctx } = createTestContext();
+        const state = getState(ctx);
+
+        state.produce(s => {
+            s.players.white.cat.supply = 3;
+        });
+
+        const promptPromise = waitForPrompt(ctx);
+        const runPromise = ctx.commands.run<{winner: WinnerType}>('turn white');
+
+        const promptEvent = await promptPromise;
+        promptEvent.resolve({ name: 'play', params: ['white', 2, 2, 'cat'], options: {}, flags: {} });
+
+        const result = await runPromise;
+        expect(result.success).toBe(true);
+        expect(getParts(state).length).toBe(1);
+        expect(getParts(state)[0].id).toBe('white-cat-1');
+        expect(getParts(state)[0].value.pieceType).toBe('cat');
+        expect(state.value.players.white.cat.supply).toBe(2);
+    });
+
+    it('should reject placing a cat when supply is empty', async () => {
+        const { ctx } = createTestContext();
+        const state = getState(ctx);
+
+        state.produce(s => {
+            s.players.white.cat.supply = 0;
+        });
+
+        const promptPromise = waitForPrompt(ctx);
+        const runPromise = ctx.commands.run<{winner: WinnerType}>('turn white');
+
+        const promptEvent1 = await promptPromise;
+        promptEvent1.resolve({ name: 'play', params: ['white', 0, 0, 'cat'], options: {}, flags: {} });
+
+        const promptEvent2 = await waitForPrompt(ctx);
+        expect(promptEvent2).not.toBeNull();
+
+        promptEvent2.reject(new Error('test end'));
+
+        const result = await runPromise;
+        expect(result.success).toBe(false);
     });
 });