Guess the random number

Emmanuel Valverde

Emmanuel Valverde

See author's bio and posts

What do we want to build?

We want to create a small game. The game consists of a player trying to guess a random number. The player will have three attempts to guess the number. If the number is correctly guessed, then the player wins, if not, the player loses.

If the player fails to guess the number, the game must notify the user if the number it's higher or lower.

What do we try to work out with this kata?

This kata is meant to work on test doubles. But it can also be solved without them. Also, it's an excellent kata to work on Primitive obsession and baby steps.

Business rules

  • The user starts playing, the game generates a random number that must not change until the game it's over.
  • If the user guesses the number the player wins.
  • If the user does not guess the number the system would have to notify the user if the number it's higher or lower.
  • If the user does not guess the number on three intents it will lose.

Use cases

The player wins on the first move

As player
I play the number 5
the player wins

 

 

Initial state Player wins on the first move
Initial state Player won on the first Intent

 

The player wins not on the first intent

As player
I play a 10
I play a 3
I play a 5
the player wins

 

Initial state Player first move Player second move Player third move
Initial state Player first move not guesses the number Player fails on second intent Player wins on last intent

 

The player loses the game

As player
I play a 10
I play a 3
I play a 5
The player loses

 

Initial state Player first move Player second move Player third move
Initial state Player first move not guesses the number Player second move number higher Player fails on the last intent and loses the game

 

Possible API of the class

public class GuessingNumberGame {
GuessingNumberGame(RandomNumberGenerator generator){}
public String guessNumber(int guessedNumber) {}
}

What can I practice with this kata

  • Working with collaborators
  • Baby steps
  • Object Calisthenics
  • Test doubles