• 12 hours
  • Medium

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Last updated on 3/3/22

Test your React Application with Jest and React Testing Library

Evaluated skills

  • Test your React app with Jest and React Testing Library
  • Question 1

    Which of these statements are false?

    Careful, there are several correct answers.
    • If the name of your test ends with  .test.js   , you can put your file wherever you like in  /src  .

    • Unit testing is the type of test that takes the longest to write.

    • Tests provide security when modifying a codebase.

    • You can call your test files whatever you like, as long as you put them in a   _test_  folder.

    • Continuous integration is a solution that triggers testing while you write your code.

  • Question 2

    You’ve written a  timesThree  function that multiplies the number passed as an argument by 3. 

    export function timesThree(numberToMultiply) {
     return numberToMultiply * 3
    }
    


    You create an   index.test.js   file. Which code snippets will test this function for you?

    Careful, there are several correct answers.
    • it('should multiply by 3', () => {
         const expected = 6
         expect(timesThree(2)).toBe(expected)
       })
      
    • describe('The timesThree function', () => {
       test('should multiply by 3', () => {
         const expected = 6
         expect(timesThree(2)).toBe(expected)
       })
      })
      
    • describe('The timesThree function', () => {
       test(() => {
         const expected = 6
         expect(timesThree(2)).toBe(expected)
       })
      })
      
    • test('should multiply by 3', () => {
         expect(timesThree(2)) === 6
       })
      
  • Question 3

    Complete the phrase with the correct answers: Code coverage…

    Careful, there are several correct answers.
    • should be 100 % for a modification to be considered reliable.

    • is a good indicator of the lines of code that are covered by tests.

    • is launched with the command   yarn test -- --coverage  .

    • needs to be installed with  yarn add  --dev jest/coverage  .

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