diff --git a/package.json b/package.json
index 590c6ae..0002717 100644
--- a/package.json
+++ b/package.json
@@ -3,7 +3,6 @@
   "version": "0.1.0",
   "private": true,
   "dependencies": {
-    "@types/jest": "24.0.18",
     "@types/node": "12.7.12",
     "@types/react": "16.9.5",
     "@types/react-dom": "16.9.1",
@@ -19,8 +18,15 @@
     "start": "react-scripts start",
     "build": "react-scripts build",
     "test": "react-scripts test",
-    "eject": "react-scripts eject"
+    "test-nowatch": "CI=true react-scripts test --env=jsdom",
+    "eject": "react-scripts eject",
+    "lint": "eslint --ext .js,.tsx,.ts,.tsx src/"
   },
+  "pre-commit": [
+    "lint",
+    "test-nowatch",
+    "build"
+  ],
   "eslintConfig": {
     "extends": "react-app"
   },
@@ -37,6 +43,7 @@
     ]
   },
   "devDependencies": {
+    "@types/jest": "^24.0.18",
     "@types/react-redux": "^7.1.4",
     "@types/redux": "^3.6.0",
     "@types/styled-components": "^4.1.19",
@@ -48,6 +55,7 @@
     "eslint-plugin-jsx-a11y": "^6.2.3",
     "eslint-plugin-react": "^7.16.0",
     "eslint-plugin-react-hooks": "^1.7.0",
-    "jest": "^24.9.0"
+    "jest": "^24.9.0",
+    "pre-commit": "^1.2.2"
   }
 }
diff --git a/src/App.tsx b/src/App.tsx
index f1aeb30..8b7cdaf 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -21,6 +21,7 @@ const StyledApp = styled.div`
 
 interface StateProps {
   currentPlayer: Player;
+  winner: Winner;
 }
 
 interface ActionProps {
@@ -29,10 +30,12 @@ interface ActionProps {
 
 type Props = StateProps & ActionProps;
 
-const App: React.FC<Props> = ({ currentPlayer, startGame }) => (
+const App: React.FC<Props> = ({ currentPlayer, startGame, winner }) => (
   <StyledApp>
     <GlobalStyle />
-    <h1>{currentPlayer}</h1>
+    <h1>
+      {currentPlayer} - {winner}
+    </h1>
     <button type="button" onClick={startGame}>
       Reset Game
     </button>
@@ -42,6 +45,7 @@ const App: React.FC<Props> = ({ currentPlayer, startGame }) => (
 
 const mapStateToProps = (state: GameState): StateProps => ({
   currentPlayer: state.currentPlayer,
+  winner: state.winner,
 });
 
 const mapActionsToProps = {
diff --git a/src/components/Board.spec.tsx b/src/components/Board.spec.tsx
new file mode 100644
index 0000000..7861f7f
--- /dev/null
+++ b/src/components/Board.spec.tsx
@@ -0,0 +1,6 @@
+describe('My Connected React-Redux Component', () => {
+  it('should render with given state from Redux store', () => {
+  });
+  it('should dispatch an action on button click', () => {
+  });
+});
diff --git a/src/components/Cell.spec.tsx b/src/components/Cell.spec.tsx
new file mode 100644
index 0000000..dc0f00a
--- /dev/null
+++ b/src/components/Cell.spec.tsx
@@ -0,0 +1,4 @@
+describe('My Connected React-Redux Component', () => {
+  it('should render with given state from Redux store', () => {});
+  it('should dispatch an action on button click', () => {});
+});
diff --git a/src/lib/scoring.ts b/src/lib/scoring.ts
index b19423d..6bb2a2e 100644
--- a/src/lib/scoring.ts
+++ b/src/lib/scoring.ts
@@ -1,7 +1,7 @@
 import { Board, Cell, Cells, empty, Rows } from './Board';
 import { Player, Winner, tie, undetermined } from './Player';
 
-export interface IBoardSummary {
+export interface BoardSummary {
   horizontal: Rows;
   vertical: Rows;
   diagonal: Rows;
@@ -52,8 +52,8 @@ export const getWinnerFromLines = (lines: Rows): Winner => {
   return undetermined;
 };
 
-export const getBoardSummary = (board: Board): IBoardSummary => {
-  const summary: IBoardSummary = {
+export const getBoardSummary = (board: Board): BoardSummary => {
+  const summary: BoardSummary = {
     horizontal: [[], [], []],
     vertical: [[], [], []],
     diagonal: [[], []],
diff --git a/src/redux/game.spec.ts b/src/redux/game.spec.ts
new file mode 100644
index 0000000..80d304c
--- /dev/null
+++ b/src/redux/game.spec.ts
@@ -0,0 +1,129 @@
+import { reducer, GameState, actions } from './game';
+import { Player, tie, undetermined } from '../lib/Player';
+import { empty, createEmptyBoard } from '../lib/Board';
+import { getBoardSummary, BoardSummary } from '../lib/scoring';
+
+jest.mock('../lib/scoring');
+
+const mockedGetBoardSummary = <jest.Mock<BoardSummary>>getBoardSummary;
+
+describe('reducer with name', () => {
+  describe('START_GAME', () => {
+    it('must reset the game state', () => {
+      const state: GameState = {
+        currentPlayer: Player.O,
+        activeGame: false,
+        board: [],
+        winner: tie,
+      };
+      const action = actions.startGame();
+      const updatedState = reducer(state, action);
+      expect(updatedState).toEqual({
+        board: [[empty, empty, empty], [empty, empty, empty], [empty, empty, empty]],
+        winner: undetermined,
+        activeGame: true,
+        currentPlayer: Player.X,
+      });
+    });
+  });
+  describe('END_GAME', () => {
+    it('must set the activeGame flag to false', () => {
+      const state: GameState = {
+        currentPlayer: Player.O,
+        activeGame: true,
+        board: [],
+        winner: tie,
+      };
+      const action = actions.endGame();
+      const updatedState = reducer(state, action);
+      expect(updatedState).toEqual({ ...state, activeGame: false });
+    });
+  });
+  describe('NEXT_PLAYER', () => {
+    it('must toggle the player everytime NEXT_PLAYER is called', () => {
+      const state: GameState = {
+        currentPlayer: Player.O,
+        activeGame: true,
+        board: [],
+        winner: tie,
+      };
+      const action = actions.nextPlayer();
+      let updatedState = reducer(state, action);
+      expect(updatedState.currentPlayer).toEqual(Player.X);
+      updatedState = reducer(updatedState, action);
+      expect(updatedState.currentPlayer).toEqual(Player.O);
+      updatedState = reducer(updatedState, action);
+      expect(updatedState.currentPlayer).toEqual(Player.X);
+    });
+    it('must not toggle the player when the game is not active anymore', () => {
+      const state: GameState = {
+        currentPlayer: Player.O,
+        activeGame: false,
+        board: [],
+        winner: tie,
+      };
+      const action = actions.nextPlayer();
+      let updatedState = reducer(state, action);
+      expect(updatedState.currentPlayer).toEqual(Player.O);
+      updatedState = reducer(updatedState, action);
+      expect(updatedState.currentPlayer).toEqual(Player.O);
+      updatedState = reducer(updatedState, action);
+      expect(updatedState.currentPlayer).toEqual(Player.O);
+    });
+  });
+  describe('UPDATE_BOARD', () => {
+    it('must mark an empty cell with the specified player', () => {
+      const state: GameState = {
+        currentPlayer: Player.O,
+        activeGame: true,
+        board: createEmptyBoard(),
+        winner: tie,
+      };
+      const action = actions.updateBoard(2, 1, Player.O);
+      const updatedState = reducer(state, action);
+      expect(updatedState).toEqual({
+        ...state,
+        board: [[empty, empty, empty], [empty, empty, empty], [empty, Player.O, empty]],
+      });
+    });
+    it('must NOT mark a cell when it is not empty', () => {
+      const state: GameState = {
+        currentPlayer: Player.O,
+        activeGame: true,
+        board: [[empty, empty, empty], [empty, empty, empty], [empty, Player.O, empty]],
+        winner: tie,
+      };
+      const action = actions.updateBoard(2, 1, Player.X);
+      const updatedState = reducer(state, action);
+      expect(updatedState).toEqual({
+        ...state,
+        board: [[empty, empty, empty], [empty, empty, empty], [empty, Player.O, empty]],
+      });
+    });
+    it('must NOT mark a cell when the game is not active anymore', () => {
+      const state: GameState = {
+        currentPlayer: Player.O,
+        activeGame: false,
+        board: [[empty, empty, empty], [empty, empty, empty], [empty, Player.O, empty]],
+        winner: tie,
+      };
+      const action = actions.updateBoard(2, 1, Player.X);
+      const updatedState = reducer(state, action);
+      expect(updatedState).toEqual(state);
+    });
+  });
+  describe('DETERMINE_WINNER', () => {
+    it('must use the external scroring logic to decide if there is a winner', () => {
+      const state: GameState = {
+        currentPlayer: Player.O,
+        activeGame: true,
+        board: [],
+        winner: undetermined,
+      };
+      mockedGetBoardSummary.mockReturnValueOnce({ horizontal: [], vertical: [], diagonal: [], winner: Player.X });
+      const action = actions.determineWinner();
+      const updatedState = reducer(state, action);
+      expect(updatedState).toEqual({ ...state, winner: Player.X });
+    });
+  });
+});
diff --git a/src/redux/game.ts b/src/redux/game.ts
index 4f99dc8..fcc1e19 100644
--- a/src/redux/game.ts
+++ b/src/redux/game.ts
@@ -61,7 +61,7 @@ const defaultState: IGameState = {
 
 export const reducer: Reducer<IGameState, Action> = (state: IGameState = defaultState, action: Action): IGameState => {
   if (action.type === START_GAME) {
-    return { ...state, board: createEmptyBoard(), activeGame: true };
+    return { ...state, board: createEmptyBoard(), activeGame: true, winner: undetermined, currentPlayer: Player.X };
   }
   if (action.type === END_GAME) {
     return { ...state, activeGame: false };