diff --git a/pytest.ini b/pytest.ini
new file mode 100644
index 0000000..3f7a136
--- /dev/null
+++ b/pytest.ini
@@ -0,0 +1,6 @@
+[pytest]
+testpaths = tests
+python_files = test_*.py
+python_classes = Test*
+python_functions = test_*
+addopts = -v --tb=short 
\ No newline at end of file
diff --git a/run_game.py b/run_game.py
new file mode 100644
index 0000000..62e3d9e
--- /dev/null
+++ b/run_game.py
@@ -0,0 +1,34 @@
+#!/usr/bin/env python3
+import argparse
+from src.game import Game
+
+def main():
+    parser = argparse.ArgumentParser(description='Run AI Snake Game')
+    parser.add_argument('--test', action='store_true',
+                       help='Run game in test mode (smaller window, faster speed)')
+    parser.add_argument('--debug', action='store_true',
+                       help='Run game in debug mode (shows grid and additional info)')
+    parser.add_argument('--ai-only', action='store_true',
+                       help='Start directly in AI mode (skips menu)')
+    
+    args = parser.parse_args()
+    
+    # Create game instance
+    game = Game()
+    
+    # Apply test mode settings
+    if args.test:
+        game.width = 400
+        game.height = 300
+        game.block_size = 20
+        game.fps = 30
+    
+    # Apply debug mode settings
+    if args.debug:
+        game.debug = True  # Will need to add debug support to Game class
+    
+    # Run the game
+    game.run()
+
+if __name__ == "__main__":
+    main() 
\ No newline at end of file
diff --git a/src/game.py b/src/game.py
index 2fc3a49..37a5563 100644
--- a/src/game.py
+++ b/src/game.py
@@ -32,6 +32,9 @@ class Game:
         self.state = GameState.MENU  # Start in menu state
         self.running = True
         self.game_mode = None
+        
+        # Debug mode
+        self.debug = False
 
     def reset_game(self):
         """Reset the game state for a new game"""
@@ -40,6 +43,29 @@ class Game:
         self.food.spawn(self.width, self.height, self.snake.body)
         self.score = 0
 
+    def draw_grid(self):
+        """Draw the game grid (debug mode)"""
+        for x in range(0, self.width, self.block_size):
+            pygame.draw.line(self.screen, (50, 50, 50), (x, 0), (x, self.height))
+        for y in range(0, self.height, self.block_size):
+            pygame.draw.line(self.screen, (50, 50, 50), (0, y), (self.width, y))
+
+    def draw_debug_info(self):
+        """Draw debug information"""
+        font = pygame.font.Font(None, 24)
+        debug_info = [
+            f"FPS: {int(self.clock.get_fps())}",
+            f"Snake Length: {len(self.snake.body)}",
+            f"Snake Head: {self.snake.body[0]}",
+            f"Food Pos: {self.food.position}",
+            f"Game State: {self.state.name}",
+            f"Game Mode: {self.game_mode.name if self.game_mode else 'None'}"
+        ]
+        
+        for i, text in enumerate(debug_info):
+            surface = font.render(text, True, (0, 255, 0))
+            self.screen.blit(surface, (10, self.height - 150 + i * 25))
+
     def handle_events(self):
         for event in pygame.event.get():
             if event.type == pygame.QUIT:
@@ -52,6 +78,8 @@ class Game:
                         self.state = GameState.PLAYING
                     elif self.state == GameState.MENU:
                         self.running = False
+                elif event.key == pygame.K_F3:  # Toggle debug mode
+                    self.debug = not self.debug
                 
                 if self.state == GameState.MENU:
                     # Handle menu input
@@ -101,6 +129,10 @@ class Game:
         # Clear screen
         self.screen.fill((0, 0, 0))  # Black background
         
+        # Draw grid in debug mode
+        if self.debug and self.state != GameState.MENU:
+            self.draw_grid()
+        
         if self.state == GameState.MENU:
             self.menu.draw(self.screen)
         
@@ -138,6 +170,10 @@ class Game:
             self.screen.blit(score_text, score_rect)
             self.screen.blit(restart_text, restart_rect)
         
+        # Draw debug info
+        if self.debug:
+            self.draw_debug_info()
+        
         # Update display
         pygame.display.flip()
 
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..6c0f708
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,29 @@
+import pytest
+import pygame
+import sys
+import os
+
+# Add src directory to Python path
+sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '..')))
+
+@pytest.fixture(autouse=True)
+def pygame_init():
+    """Initialize pygame for all tests"""
+    pygame.init()
+    yield
+    pygame.quit()
+
+@pytest.fixture
+def game_config():
+    """Basic game configuration"""
+    return {
+        'width': 800,
+        'height': 600,
+        'block_size': 20,
+        'fps': 60
+    }
+
+@pytest.fixture
+def mock_screen(game_config):
+    """Create a mock pygame screen"""
+    return pygame.Surface((game_config['width'], game_config['height'])) 
\ No newline at end of file
diff --git a/tests/test_food.py b/tests/test_food.py
new file mode 100644
index 0000000..4e7ed72
--- /dev/null
+++ b/tests/test_food.py
@@ -0,0 +1,58 @@
+import pytest
+from src.food import Food
+
+def test_food_initialization():
+    """Test food initialization"""
+    food = Food(20)
+    assert food.block_size == 20
+    assert food.color == (255, 0, 0)  # Default red color
+    assert food.position == (0, 0)  # Default position
+
+def test_food_spawn():
+    """Test food spawning mechanics"""
+    food = Food(20)
+    width, height = 800, 600
+    snake_body = [(100, 100), (120, 100)]  # Mock snake body
+    
+    # Test spawning
+    food.spawn(width, height, snake_body)
+    
+    # Check if food is within bounds
+    assert 0 <= food.position[0] < width
+    assert 0 <= food.position[1] < height
+    
+    # Check if position aligns with grid
+    assert food.position[0] % food.block_size == 0
+    assert food.position[1] % food.block_size == 0
+    
+    # Check if food doesn't spawn on snake
+    assert food.position not in snake_body
+
+def test_food_collision():
+    """Test food collision detection"""
+    food = Food(20)
+    food.position = (100, 100)
+    
+    # Test collision
+    assert food.check_collision((100, 100)) == True
+    
+    # Test no collision
+    assert food.check_collision((120, 120)) == False
+
+def test_food_spawn_full_grid():
+    """Test food spawning when grid is mostly occupied"""
+    food = Food(20)
+    width, height = 60, 60  # Small grid
+    
+    # Create a snake that occupies most of the grid
+    snake_body = [(x, y) for x in range(0, 60, 20) for y in range(0, 40, 20)]
+    
+    # Leave one spot free at (40, 40)
+    free_spot = (40, 40)
+    assert free_spot not in snake_body
+    
+    # Spawn food
+    food.spawn(width, height, snake_body)
+    
+    # Food should spawn in the only free spot
+    assert food.position == free_spot 
\ No newline at end of file
diff --git a/tests/test_snake.py b/tests/test_snake.py
new file mode 100644
index 0000000..2495817
--- /dev/null
+++ b/tests/test_snake.py
@@ -0,0 +1,74 @@
+import pytest
+from src.snake import Snake, Direction
+
+def test_snake_initialization():
+    """Test snake initialization with default values"""
+    snake = Snake((100, 100), 20)
+    assert snake.block_size == 20
+    assert snake.direction == Direction.RIGHT
+    assert len(snake.body) == 1
+    assert snake.body[0] == (100, 100)
+    assert not snake.growing
+
+def test_snake_movement():
+    """Test snake movement in different directions"""
+    snake = Snake((100, 100), 20)
+    
+    # Test right movement (default direction)
+    snake.move(100)  # time parameter
+    assert snake.body[0] == (120, 100)
+    
+    # Test down movement
+    snake.change_direction(Direction.DOWN)
+    snake.move(200)
+    assert snake.body[0] == (120, 120)
+    
+    # Test left movement
+    snake.change_direction(Direction.LEFT)
+    snake.move(300)
+    assert snake.body[0] == (100, 120)
+    
+    # Test up movement
+    snake.change_direction(Direction.UP)
+    snake.move(400)
+    assert snake.body[0] == (100, 100)
+
+def test_snake_growth():
+    """Test snake growth when eating food"""
+    snake = Snake((100, 100), 20)
+    original_length = len(snake.body)
+    
+    snake.grow()
+    snake.move(100)
+    
+    assert len(snake.body) == original_length + 1
+
+def test_snake_collision():
+    """Test snake collision detection"""
+    snake = Snake((100, 100), 20)
+    
+    # Test wall collision
+    assert snake.check_collision(200, 200) == False  # No collision
+    snake.body[0] = (-20, 100)  # Move outside left wall
+    assert snake.check_collision(200, 200) == True
+    
+    # Test self collision
+    snake = Snake((100, 100), 20)
+    snake.body = [(100, 100), (120, 100), (120, 120), (100, 120), (100, 100)]
+    assert snake.check_collision(200, 200) == True
+
+def test_invalid_direction_change():
+    """Test that snake cannot reverse direction"""
+    snake = Snake((100, 100), 20)
+    
+    # Try to change to opposite direction (LEFT while going RIGHT)
+    snake.change_direction(Direction.LEFT)
+    assert snake.direction == Direction.RIGHT
+    
+    # Valid direction change
+    snake.change_direction(Direction.DOWN)
+    assert snake.direction == Direction.DOWN
+    
+    # Try to change to opposite direction (UP while going DOWN)
+    snake.change_direction(Direction.UP)
+    assert snake.direction == Direction.DOWN 
\ No newline at end of file