ContextQMD
Back to Freecodecamp

Test if an Object is an Instance of a Constructor

curriculum/challenges/english/blocks/quality-assurance-and-testing-with-chai/587d824e367417b2b2512c57.md

latest2.3 KB
Original Source

--description--

As a reminder, this project is being built upon the following starter project cloned from <a href="https://github.com/freeCodeCamp/boilerplate-mochachai/" target="_blank" rel="noopener noreferrer nofollow">GitHub</a>.

#instanceOf asserts that an object is an instance of a constructor.

--instructions--

Within tests/1_unit-tests.js under the test labeled #18 in the Objects suite, change each assert to either assert.instanceOf or assert.notInstanceOf to make the test pass (should evaluate to true). Do not alter the arguments passed to the asserts.

--hints--

All tests should pass.

js
const response = await fetch(code + '/_api/get-tests?type=unit&n=17');
if (!response.ok) {
  throw Error(await response.text());
}
const data = await response.json();
assert.equal(data.state, 'passed');

You should choose the correct method for the first assertion - instanceOf vs. notInstanceOf.

js
const response = await fetch(code + '/_api/get-tests?type=unit&n=17');
if (!response.ok) {
  throw Error(await response.text());
}
const data = await response.json();
assert.equal(
  data.assertions[0].method,
  'notInstanceOf',
  'myCar is not an instance of Plane'
);

You should choose the correct method for the second assertion - instanceOf vs. notInstanceOf.

js
const response = await fetch(code + '/_api/get-tests?type=unit&n=17');
if (!response.ok) {
  throw Error(await response.text());
}
const data = await response.json();
assert.equal(
  data.assertions[1].method,
  'instanceOf',
  'airlinePlane is an instance of Plane'
);

You should choose the correct method for the third assertion - instanceOf vs. notInstanceOf.

js
const response = await fetch(code + '/_api/get-tests?type=unit&n=17');
if (!response.ok) {
  throw Error(await response.text());
}
const data = await response.json();
assert.equal(
  data.assertions[2].method,
  'instanceOf',
  'everything is an Object in JavaScript...'
);

You should choose the correct method for the fourth assertion - instanceOf vs. notInstanceOf.

js
const response = await fetch(code + '/_api/get-tests?type=unit&n=17');
if (!response.ok) {
  throw Error(await response.text());
}
const data = await response.json();
assert.equal(
  data.assertions[3].method,
  'notInstanceOf',
  'myCar.wheels is not an instance of String'
);