Precourse: Closures Part 2

Objectives

By the end of this assignment, you should be able to:

• Create tests
• Understand test syntax
• Pass the tests you write
• Predict the values of variables within closure scopes through multiple invocations

Exercises

Now that you've written some closures and have passed some tests we created for you, you'll gain some practice writing unit tests alongside regular code.

✅ This assignment will start you off with tests and then give you a chance to write them.

Getting Started

• These tests will be found in specs/tests.js and can be run by opening up SpecRunner.html in your browser.

Basic Requirements

• gameGenerator: Below is some very basic code for a guessing game. Let's make it more complex using closures. gameGenerator should create guessing games using closures so you can make multiple games. Remember to write your tests. Your game should:

  • take a number input that provides the 'upper bound' (limit)
  • generate a random number between 0 and the upper bound
  • have a method reset that resets the game (new winning number, reset guesses, same upper bound)
  • have a method giveUp that returns the correct number and resets the game
  • have a method guess that allows you to guess the number and returns true or false if the guess is right or wrong
  • keep track of how many guesses have been made
  • have a method numGuesses that provides a way to see the number of guesses that have been made

  function randomInteger(n) {
    return Math.floor(Math.random() * (n + 1));
  }
  
  const upperBound = 5;
  
  function guessThisNumber(n) {
    if (n > upperBound) {
      return {
        message: `Wrong. Please try a number between 0 and ${upperBound}.`,
        status: false
      };
    } else if (n === randomInteger(upperBound)) {
      return {
        message: "You win!",
        status: true
      };
    }
  
    return {
      message: `Wrong. Please try a number between 0 and ${upperBound}.`,
      status: false
    };
  }

• accountGenerator: You'll be provided with a function called accountGenerator in src/closures.js. Please add more functionality:

  • Add function getBalance that returns the current balance

  • Change withdraw to return a transaction object (see below)

  • Change deposit to return a transaction object (see below)

  • Implement a function transactionHistory to get the last n withdrawals or deposits 💵 (see below)

  • Implement a function averageTransaction that determines the average withdrawal and deposit amounts 💰. IMPORTANT: Only approved transactions count towards the total!. It should return an object that looks like

    {
      deposit: number,
      withdrawal: number
    }

  • Use the Date object to incorporate a key time into the transactions 📅

  A single transaction should be represented by an object. For instance:

  const exampleDeposit = {
    type: "deposit",
    amount: 1000,
    before: 500,
    after: 1500,
    status: "approved"
  };
  
  const exampleWithdrawal = {
    type: "withdrawal",
    amount: 1000,
    before: 520,
    after: 520,
    status: "denied"
  };

  Transaction history, for instance:

  const account = accountGenerator(100);
  account.transactionHistory(2); // => [{...}, {...}]

  Remember to write tests!☝️

Resources

• Let's Learn JS Closures! (Free Code Camp)
• Jasmine unit testing tutorial
• Jasmine documentation