Why testing matters in Node.js - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the testing function from Node.js.

Node.js

import { [1] } from 'node:test';

Drag options to blanks, or click blank then click option'

Atest

Bcheck

Crun

Dassert

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'run' or 'check' which are not valid imports.

Trying to import 'assert' here instead of 'test'.

The test function is used to define tests in Node.js native test runner.

2fill in blank

medium

Complete the code to write a simple test that checks if 2 + 2 equals 4.

Node.js

test('simple addition', () => {
  if (2 + 2 !== [1]) throw new Error('Fail');
});

Drag options to blanks, or click blank then click option'

A4

B5

C3

D6

Attempts:

3 left

💡 Hint

Common Mistakes

Using 5 or 3 which are incorrect sums.

Confusing the expected value with something else.

The test checks if 2 + 2 equals 4, so the correct value is 4.

3fill in blank

hard

Fix the error in the test by completing the assertion method.

Node.js

import assert from 'node:assert';

test('check truth', () => {
  assert.[1](true);
});

Drag options to blanks, or click blank then click option'

Aequal

Bok

Cfail

DnotEqual

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'fail' which always throws an error.

Using 'equal' without a second argument.

The assert.ok() method checks if the value is truthy.

4fill in blank

hard

Fill both blanks to create a test that checks if a function throws an error.

Node.js

test('throws error', () => {
  assert.[1](() => {
    throw new Error('Oops');
  }, [2]);
});

Drag options to blanks, or click blank then click option'

Athrows

BdoesNotThrow

Cok

Dequal

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'doesNotThrow' which expects no error.

Using 'equal' which is not for error checking.

assert.throws() checks if the function throws an error. The second argument is usually a validation function or constructor, here simplified as throws to check the error type.

5fill in blank

hard

Fill all three blanks to write a test that asynchronously checks a promise resolves to 'done'.

Node.js

test('async test', async () => {
  const result = await Promise.resolve([1]);
  assert.[2](result, [3]);
});

Drag options to blanks, or click blank then click option'

A'done'

BstrictEqual

C'done!'

Dequal

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'done!' instead of 'done'.

Using 'equal' which is less strict than 'strictEqual'.

The promise resolves to the string 'done'. The assertion uses strictEqual to check exact equality with 'done'.