How to use toHaveLengthAsync method in Jest

Best JavaScript code snippet using jest

success.test.js

Source:success.test.js Github

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...6 */7import {toHaveLengthAsync} from '../matchers';8expect.extend({toHaveLengthAsync});9it('works with expected non promise values', () =>10 expect([1]).toHaveLengthAsync(Promise.resolve(1)));11it('works with expected non promise values and not', () =>12 expect([1, 2]).not.toHaveLengthAsync(Promise.resolve(1)));13it('works with expected promise values', () =>14 expect(Promise.resolve([1])).resolves.toHaveLengthAsync(Promise.resolve(1)));15it('works with expected promise values and not', () =>16 expect(Promise.resolve([1, 2])).resolves.not.toHaveLengthAsync(17 Promise.resolve(1)...

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failure.test.js

Source:failure.test.js Github

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...6 */7import {toHaveLengthAsync} from '../matchers';8expect.extend({toHaveLengthAsync});9it('fail with expected non promise values', () =>10 expect([1]).toHaveLengthAsync(Promise.resolve(2)));11it('fail with expected non promise values and not', () =>12 expect([1, 2]).not.toHaveLengthAsync(Promise.resolve(2)));13it('fail with expected promise values', () =>14 expect(Promise.resolve([1])).resolves.toHaveLengthAsync(Promise.resolve(2)));15it('fail with expected promise values and not', () =>16 expect(Promise.resolve([1, 2])).resolves.not.toHaveLengthAsync(17 Promise.resolve(2)...

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  9. Jest Parameterized Tests - Avoid code duplication and fasten automation testing with Jest using parameterized tests. Parameterization allows you to trigger the same test scenario over different test configurations by incorporating parameters.
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|<p>it('check_object_of_Car', () => {</p><p> expect(newCar()).toBeInstanceOf(Car);</p><p> });</p>| | :- |

  1. Jest Hooks: Setup and Teardown - Learn how to set up conditions which needs to be followed by the test execution and incorporate a tear down function to free resources after the execution is complete.
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  8. Jest vs Mocha vs Jasmine - Learn the key differences between the most popular JavaScript-based testing frameworks i.e. Jest, Mocha, and Jasmine.
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