ユーザ入力を受け取る関数の単体テストを書くにはどうすればいいですか？

Question

"""A program to do FLAMES by accepting two names. 
F-Friends, L-Lovers, A-Admirers, M-Married Couple, E-Enemies, S-Secret Lovers 

Modified Version : Jan 11 2017 
Programmer : Selikem v 0.1.0 
""" 

def Flames(): 
    print("\nAre you READY FOR FLAMES????") 

    boyName = input("Enter the Guy's Name: ") 
    girlName = input("Enter the Lady's Name: ") 

    bName = list(boyName.lower()) #Splits name into individual characters and places it in a list 
    gName = list(girlName.lower()) 

    #Below, We remove common letters found in both names. 
    for i in bName: 
     while i in gName: 
      bName.remove(i) 
      gName.remove(i) 
      break 

    for i in gName: 
     while i in bName: 
      bName.remove(i) 
      gName.remove(i) 
      break  

    #Below Checks whether there are common letters again and removes them. 
    while True: 
     for i in bName: 
      while i in gName: 
       bName.remove(i) 
       gName.remove(i) 
       break 

     for i in gName: 
      while i in bName: 
       bName.remove(i) 
       gName.remove(i) 
     break 

    flame = bName + gName #Variable to store remaining characters after cancellation of common ones. 
    #flame = set(flame) 
    #print(len(flame)) 
    #print(bName) 
    #print(gName) 
    #print(flame) 

    while len(flame) < 50: 

     if len(flame) == 1 or len(flame) == 7 or len(flame) == 13 or len(flame) == 19 or len(flame) == 25: 
      FLAMES = "FRIENDS" 

     elif len(flame) == 2 or len(flame) == 8 or len(flame) == 14 or len(flame) == 20 or len(flame) == 26: 
      FLAMES = "LOVERS" 

     elif len(flame) == 3 or len(flame) == 9 or len(flame) == 15 or len(flame) == 21 or len(flame) == 27: 
      FLAMES = "ADMIRERS" 

     elif len(flame) == 4 or len(flame) == 10 or len(flame) == 16 or len(flame) == 22 or len(flame) == 28: 
      FLAMES = "MARRIED COUPLE" 

     elif len(flame) == 5 or len(flame) == 11 or len(flame) == 17 or len(flame) == 23 or len(flame) == 29: 
      FLAMES = "ENEMIES" 

     elif len(flame) == 6 or len(flame) == 12 or len(flame) == 18 or len(flame) == 24 or len(flame) == 30: 
      FLAMES = "SECRET ADMIRERS" 

     print("\n{} and {} are ".format(boyName, girlName) + FLAMES) 

     break 

def Play_Again(): 
    """Function that permits user to play FLAMES again""" 
    while True: 
       print("\nDo you want to play again? :") 

       answer = input("(Enter y/n to continue): ") 
       if answer == 'y' : 
        Flames() 

       else: 
        print("\nTHANK YOU FOR PLAYING!") 
        break 

Flames() 
Play_Again() 

Answer 1

ドメインモデル（何かを計算するコードの部分）からUIコードを分離します。次に、ドメインモデルをユニットテストできます。