simplified time travel function

ldgit · Dec 10, 2018 · 808410c · 808410c
1 parent 7de165d
commit 808410c
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Showing 2 changed files with 6 additions and 31 deletions.
diff --git a/src/ultimate-game.js b/src/ultimate-game.js
@@ -83,12 +83,12 @@ function updateBoardActiveStatus(boardIndex, squareIndex) {
   };
 }
 
-function timeTravel(oldState, { pointInHistory }) {
-  const newState = deepCopyGameState(oldState);
-  newState.pointInHistory = pointInHistory;
-  newState.nextPlayer = pointInHistory % 2 === 0 ? 'X' : 'O';
-
-  return newState;
+function timeTravel(state, { pointInHistory }) {
+  return {
+    ...state,
+    pointInHistory,
+    nextPlayer: pointInHistory % 2 === 0 ? 'X' : 'O',
+  };
 }
 
 function getInitialState() {
@@ -104,20 +104,6 @@ function getInitialState() {
   };
 }
 
-function deepCopyGameState(state) {
-  const newHistory = state.history.map(boardEntry => ({ boards: deepCopyGameBoards(boardEntry.boards) }));
-
-  return {
-    ...state,
-    nextPlayer: state.nextPlayer,
-    history: newHistory,
-  };
-}
-
-function deepCopyGameBoards(boards) {
-  return boards.map(board => ({ ...board, isActive: board.isActive, squares: [...board.squares] }));
-}
-
 function nextBoardIsWon(boards, { squareIndex }) {
   return !!calculateWinner(boards[squareIndex].squares);
 }

diff --git a/test/ultimate-game.test.js b/test/ultimate-game.test.js
@@ -250,17 +250,6 @@ describe('ultimate tic-tac-toe', () => {
         assert.equal(callTimeTravel(secondMoveState, { pointInHistory: 1 }).nextPlayer, 'O');
       });
 
-      it('should return a deep copy of input state', () => {
-        const newState = callPlaySquare(initialState, { boardIndex: 1, squareIndex: 8 });
-
-        const stateAfterTimeTravel = callTimeTravel(newState, { pointInHistory: 0 });
-
-        stateAfterTimeTravel.pointInHistory = 1984;
-        stateAfterTimeTravel.history[0].boards[4].squares[1] = 'modified in state returned by time travel, should not be in previus state';
-        assert.strictEqual(newState.pointInHistory, 1, 'time travel must return a *copy* of input state');
-        expect(newState.history[0].boards[4].squares[1]).to.equal(null, 'time travel must return a *deep copy* of input state');
-      });
-
       it(
         'when time traveling to past and then playing a move, should discard all history after that time travel point',
         () => {