Don't increment move count on no-op moves (ie. moves that did not change the board)

Author: Coteh

cypress/e2e/game/gameplay.cy.ts

@@ -356,4 +356,38 @@ describe("gameplay", () => {
 
         cy.get("#moveCount").should("have.text", "0");
     });
+
+    it("should not increment move count on no-op move", () => {
+        cy.visit("/", {
+            onBeforeLoad: () => {
+                const gameState: GameState = {
+                    board: [
+                        [2, 0, 0, 0],
+                        [2, 0, 0, 0],
+                        [2, 0, 0, 0],
+                        [2, 0, 0, 0],
+                    ],
+                    ended: false,
+                    won: false,
+                    score: 0,
+                    didUndo: false,
+                    achievedHighscore: false,
+                    moveCount: 0,
+                };
+                const persistentState: GamePersistentState = {
+                    highscore: 0,
+                    unlockables: {},
+                    hasPlayedBefore: true,
+                };
+                window.localStorage.setItem("game-state", JSON.stringify(gameState));
+                window.localStorage.setItem("persistent-state", JSON.stringify(persistentState));
+            },
+        });
+
+        cy.get("#moveCount").should("have.text", "0");
+
+        cy.get("body").type("{leftArrow}"); // Perform a no-op move
+
+        cy.get("#moveCount").should("have.text", "0"); // Move count should not increment
+    });
 });

src/game.ts

@@ -275,7 +275,6 @@ export const move = (direction: Direction) => {
     console.log("prev board is now", prevBoard);
 
     undoManager.pushGameState();
-    gameState.moveCount++;
 
     animationManager.resetState();
 
@@ -286,8 +285,13 @@ export const move = (direction: Direction) => {
 
     // Keep looping through movement until no more moves can be made
     prevBoard = null;
-    let numMoves = 0;
+    let numShifts = 0;
     while (!isBoardSame(gameState.board, prevBoard)) {
+        // If at least one shift was performed, then count as a move.
+        // But do not count as a move for any subsequent shifts within this move.
+        if (numShifts === 1) {
+            gameState.moveCount++;
+        }
         prevBoard = [];
         for (let i = 0; i < gameState.board.length; i++) {
             prevBoard.push(gameState.board[i].slice());
@@ -371,10 +375,10 @@ export const move = (direction: Direction) => {
             }
         }
         console.log("current board is", gameState.board);
-        numMoves++;
+        numShifts++;
     }
 
-    if (numMoves > 1) {
+    if (numShifts > 1) {
         console.log("spawn next block and check game conditions");
 
         const location = spawnManager.determineNextBlockLocation();

test/game_test.ts

@@ -332,14 +332,11 @@ describe("core game logic", () => {
         assert.strictEqual(gameState.ended, true);
         assert.strictEqual(gameState.moveCount, 1);
         // Should not be able to make any more moves upon game over
-        mockSpawnManager.determineNextBlockValue.mockImplementation(() => {
-            return 2;
-        });
         move(DIRECTION_RIGHT);
         prevBoard = JSON.parse(JSON.stringify(gameState.board));
         assert.notStrictEqual(gameState.board, prevBoard);
         assert.strictEqual(gameState.ended, true);
-        assert.strictEqual(gameState.moveCount, 2);
+        assert.strictEqual(gameState.moveCount, 1);
     });
     it("should allow player to continue the game if board is full but adjacent blocks can be merged", async () => {
         mockSpawnManager.determineNextBlockLocation.mockImplementation(() => {
@@ -572,4 +569,35 @@ describe("core game logic", () => {
         assert.strictEqual(gameState.board[2][0], 4);
         assert.strictEqual(gameState.board[3][0], 4);
     });
+    it("should not increment move count on no-op move", async () => {
+        mockSpawnManager.determineNextBlockLocation.mockImplementation(() => {
+            return {
+                x: 0,
+                y: 0,
+            };
+        });
+        mockSpawnManager.determineNextBlockValue.mockImplementation(() => {
+            return 2;
+        });
+
+        const gameState = await setupGame({
+            board: [
+                [2, 0, 0, 0],
+                [2, 0, 0, 0],
+                [2, 0, 0, 0],
+                [2, 0, 0, 0],
+            ],
+            ended: false,
+            won: false,
+            score: 0,
+            didUndo: false,
+            achievedHighscore: false,
+            moveCount: 0,
+        });
+
+        const initialMoveCount = gameState.moveCount;
+        move(DIRECTION_LEFT); // Perform a no-op move
+
+        expect(gameState.moveCount).toBe(initialMoveCount); // Move count should not increment
+    });
 });