How to announce a draw in tictactoe game?

Question

I am a beginner in Python, I know the code for TicTacToe is already available in the Internet but I would like to understand why it's not working the way I have written.

Please find the code below, the program works the problem is I am not sure how to announce if the game is Draw and if the box is already picked up by a player the other player should not use the same box by mistake, currently it can be overwritten.

import sys

def game_on():
    """User input to play the Game to stop"""
    game = False
    while game == False:
        user_request = input("Enter 'Y' to start the game, 'N' to stop: ").upper()
        if user_request == 'Y':
            return True
        elif user_request == 'N':
            print("Thanks for Playing... Good Bye...")
            game = True
        else:
            print("Wrong choice! Select either Y or N")
            game = False

test_board = ['0','1','2','3','4','5','6','7','8','9']
def display_board(board):
    """Tic_Tac_Toe board to play, it will be displayed with numbers which user can select to replace the box in the board"""
    print(board[1]+'|'+board[2]+'|'+board[3])
    print('-----')
    print(board[4]+'|'+board[5]+'|'+board[6])
    print('-----')
    print(board[7]+'|'+board[8]+'|'+board[9])

def player_1():
    """Player_1 input to select the specific box"""
    choice = 'Wrong'
    while choice.isdigit() == False:
        choice = input("Player_1 enter a number between 1 to 9: ")
        if choice.isdigit() == False:
            print("Enter the given number in the range 1 to 9: ")
    return int(choice)

def player_2():
    """Player_2 input to select the specific box"""
    choice = 'Wrong'
    while choice.isdigit() == False:
        choice = input("Player_2 enter a number between 1 to 9: ")
        if choice.isdigit() == False:
            print("Enter a given number in the range 1 to 9")
    return int(choice)

def update_user_input_player_1(test_board,position):
    """Player_1 input will be replaced with X """
    # replacement = input("If it's player 1 enter X, if it's player 2 enter O: ")
    test_board[position] = 'X'
    return test_board

def update_user_input_player_2(test_board,position):
    """Player_1 input will be replaced with Y """
    # replacement = input("If it's player 1 enter X, if it's player 2 enter O: ")
    test_board[position] = 'Y'
    return test_board

###Still don't know how to put a draw if the list still has numbers
def winner_announcement(test_board):
    """Winner will be analysed and established"""
    validate = True
    # print(validate)
    while validate == True:
        if ('X' in test_board[1] and 'X' in test_board[2] and 'X' in test_board[3]) or ('X' in test_board[4] and 'X' in test_board[5] and 'X' in test_board[6]) or ('X' in test_board[7] and 'X' in test_board[8] and 'X' in test_board[9]) or ('X' in test_board[1] and 'X' in test_board[5] and 'X' in test_board[9]) or ('X' in test_board[3] and 'X' in test_board[5] and 'X' in test_board[7]):
            print("Player 1 is the winner")
            sys.exit()
        elif ('Y' in test_board[1] and 'Y' in test_board[2] and 'Y' in test_board[3]) or ('Y' in test_board[4] and 'Y' in test_board[5] and 'Y' in test_board[6]) or ('Y' in test_board[7] and 'Y' in test_board[8] and 'Y' in test_board[9]) or ('Y' in test_board[1] and 'Y' in test_board[5] and 'Y' in test_board[9]) or ('Y' in test_board[3] and 'Y' in test_board[5] and 'Y' in test_board[7]):
            print("Player 2 is the winner")
            sys.exit()
        else:
            validate = False
        
###Function call
play = game_on()
while play == True:
    display_board(test_board)
    player__1_result = player_1()
    update_user_input_player_1(test_board,player__1_result)
    winner_announcement(test_board)
    display_board(test_board)
    player_2_result = player_2()
    update_user_input_player_2(test_board,player_2_result)
    winner_announcement(test_board)```


For the Draw, I though if I can write a condition outside the current if statement, it should work but it's simply hanging doing nothing. 

```def winner_announcement(test_board):
    """Winner will be analysed and established"""
    validate = True
    # print(validate)
    while validate == True:
        if ('X' in test_board[1] and 'X' in test_board[2] and 'X' in test_board[3]) or ('X' in test_board[4] and 'X' in test_board[5] and 'X' in test_board[6]) or ('X' in test_board[7] and 'X' in test_board[8] and 'X' in test_board[9]) or ('X' in test_board[1] and 'X' in test_board[5] and 'X' in test_board[9]) or ('X' in test_board[3] and 'X' in test_board[5] and 'X' in test_board[7]):
            print("Player 1 is the winner")
            sys.exit()
        elif ('Y' in test_board[1] and 'Y' in test_board[2] and 'Y' in test_board[3]) or ('Y' in test_board[4] and 'Y' in test_board[5] and 'Y' in test_board[6]) or ('Y' in test_board[7] and 'Y' in test_board[8] and 'Y' in test_board[9]) or ('Y' in test_board[1] and 'Y' in test_board[5] and 'Y' in test_board[9]) or ('Y' in test_board[3] and 'Y' in test_board[5] and 'Y' in test_board[7]):
            print("Player 2 is the winner")
            sys.exit()
    else:
        print("Game Draw")
        validate = False```

Answer 1

Here I have modified many parts of your given code, added a few more conditions to check for occupancy and valid range input. Also added "draw" condition and made code more cleaner:

import sys
import numpy as np


def game_on():
    """User input to play the Game to stop"""
    game = False
    while not game:  # "while not False" ==> "while True"
        user_request = input("Enter 'Y' to start the game, 'N' to stop: ").upper()
        if user_request == 'Y':
            return True
        elif user_request == 'N':
            print("Thanks for Playing... Good Bye...")
            break
        else:
            print("Wrong choice! Select either Y or N")


test_board = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
draw_check = test_board[:]
draw_check[0] = '1'


def display_board(board):
    """Tic_Tac_Toe board to play, it will be displayed with numbers which user can select to replace the box in the board"""
    print(board[1] + '|' + board[2] + '|' + board[3])
    print('-----')
    print(board[4] + '|' + board[5] + '|' + board[6])
    print('-----')
    print(board[7] + '|' + board[8] + '|' + board[9])


def player_1():
    """Player_1 input to select the specific box"""
    choice = input("Player_1 enter a number between 1 to 9: ")
    while not choice.isdigit() or int(choice) > 9:
        choice = input("Player_1 enter a number between 1 to 9: ")
    return int(choice)


def player_2():
    """Player_2 input to select the specific box"""
    choice = input("Player_2 enter a number between 1 to 9: ")
    while not choice.isdigit() or int(choice) > 9:
        choice = input("Player_2 enter a number between 1 to 9: ")
    return int(choice)


def update_user_input_player_1(test_board, position):
    """Player_1 input will be replaced with X """
    # replacement = input("If it's player 1 enter X, if it's player 2 enter O: ")
    while not test_board[position].isdigit():
        print('Location is occupied!')
        position = player_1()
    test_board[position] = 'X'
    return test_board


def update_user_input_player_2(test_board, position):
    """Player_1 input will be replaced with Y """
    # replacement = input("If it's player 1 enter X, if it's player 2 enter O: ")
    while not test_board[position].isdigit():
        print('Location is occupied!')
        position = player_2()
    test_board[position] = 'Y'
    return test_board


###Still don't know how to put a draw if the list still has numbers
def winner_announcement(test_board):
    """Winner will be analysed and established"""
    validate = True
    # print(validate)
    while validate:  # "while True"
        if ('X' in test_board[1] and 'X' in test_board[2] and 'X' in test_board[3]) or (
                'X' in test_board[4] and 'X' in test_board[5] and 'X' in test_board[6]) or (
                'X' in test_board[7] and 'X' in test_board[8] and 'X' in test_board[9]) or (
                'X' in test_board[1] and 'X' in test_board[5] and 'X' in test_board[9]) or (
                'X' in test_board[3] and 'X' in test_board[5] and 'X' in test_board[7]):
            print("Player 1 is the winner")
            sys.exit()
        elif ('Y' in test_board[1] and 'Y' in test_board[2] and 'Y' in test_board[3]) or (
                'Y' in test_board[4] and 'Y' in test_board[5] and 'Y' in test_board[6]) or (
                'Y' in test_board[7] and 'Y' in test_board[8] and 'Y' in test_board[9]) or (
                'Y' in test_board[1] and 'Y' in test_board[5] and 'Y' in test_board[9]) or (
                'Y' in test_board[3] and 'Y' in test_board[5] and 'Y' in test_board[7]):
            print("Player 2 is the winner")
            sys.exit()
        elif not (np.array(draw_check) == test_board).any():
            print("It's a Draw!")
            sys.exit()
        else:
            validate = False


###Function call
play = game_on()

while play == True:
    display_board(test_board)
    player__1_result = player_1()
    update_user_input_player_1(test_board, player__1_result)
    winner_announcement(test_board)
    display_board(test_board)
    player_2_result = player_2()
    update_user_input_player_2(test_board, player_2_result)
    winner_announcement(test_board)