How to test simple boolean functions?

问题

Im having some issues to understand testing, since I almost never find it neccessary.

If I have simple functions like

function isMovementOutOfBounds(newPosition) {
  if (newPosition[0] > input[0][0] || newPosition[0] < 0 || newPosition[1] > input[0][1] || newPosition[1] < 0) {
    return true;
  }
  return false;
}

function isMovementForbidden(forbiddenMovements, initialPosition, newPosition) {
  function isArrayInArray(arr, item) {
    const item_as_string = JSON.stringify(item);
    const contains = arr.some((ele) => JSON.stringify(ele) === item_as_string);
    return contains;
  }
  const newMovement = [initialPosition, newPosition];

  if (isArrayInArray(forbiddenMovements, newMovement)) {
    return true;
  }
  return false;
}

Should they even be tested? They have always a return, and its always boolean. So I don't understand if its really necessary to test it.

Maybe I should test for the type of input they receive?

It all seems dumb to me, how could I test those functions? Any idea of what should I look for?

回答1:

At the very least

testing helps you to make sure that your code behaves as expected under different circumstances (all kinds of inputs, including edge cases)
testing may help you to maintain touch points between your specific module and other parts of your project
be sure that while you develop your app it still fulfills your basic requirements

Just to give you a clue, as to which kind of tests you may perform, check out the following demo (which shows that your code is not functional, as of now):

mocha.setup('bdd')

const { expect } = chai

function isMovementForbidden(forbiddenMovements, initialPosition, newPosition) {
  function isArrayInArray(arr, item) {
    const item_as_string = JSON.stringify(item);
    const contains = arr.some((ele) => JSON.stringify(ele) === item_as_string);
    return contains;
  }
  const newMovement = [initialPosition, newPosition];

  if (isArrayInArray(forbiddenMovements, newMovement)) {
    return true;
  }
  return false;
}

const testSuite = [
  {
    descr: 'Should work for basic coordinates',
    input: [[[0,0],[1,1]], [2,3], [1,1]],
    output: true
  },
  {
    descr: 'Should be able to handle empty array of forbidden movements',
    input: [[], [0,0], [1,1]],
    output: false
  },
  {
    descr: 'Should be able to allow staying at current point',
    input: [[1,1], [0,0], [0,0]],
    output: false
  }
]

describe('Basic test', ()=>{
  testSuite.forEach(({input, output, descr}) => 
    it(descr, ()=>{
        expect(isMovementForbidden(...input)).to.equal(output)
    }))
})

mocha.run()

<script src="https://cdnjs.cloudflare.com/ajax/libs/mocha/8.0.1/mocha.min.js"></script><script src="https://cdnjs.cloudflare.com/ajax/libs/chai/4.2.0/chai.min.js"></script><div id="mocha"></div>

回答2:

Testing has many benefits. You may detect unnecessary code or ideally find some errors.

In this case you could test that your functions return the correct boolean, given some edge cases or some basic input.

At least one or two simple test are enough to test the function itself, if you don't want to test too much.

来源：https://stackoverflow.com/questions/63188890/how-to-test-simple-boolean-functions

标签

javascript

node.js

unit-testing

testing