jestjs – Tarik Billa

In jest, how do I use “toHaveBeenCalledWith” and only match part of an object in an array argument?

April 5, 2024 by Tarik

You can use a combination of arrayContaining and objectContaining to make this work. Reference: https://jestjs.io/docs/expect#expectarraycontainingarray https://jestjs.io/docs/expect#expectobjectcontainingobject Here is some sample code for you: function something(a, b, somefn) { somefn([{ x: a, y: b, id: ‘some-guid’ }]); } test(‘Testing something’, () => { const mockSomeFn = jest.fn(); something(2, 3, mockSomeFn); expect(mockSomeFn).toHaveBeenCalledWith( expect.arrayContaining([ expect.objectContaining({ x: 2, y: … Read more

Jest Difference Between toBeCalledWith and toHaveBeenCalledWith

January 6, 2024 by Tarik

From the docs https://jestjs.io/docs/en/expect#tohavebeencalledwitharg1-arg2- .toHaveBeenCalledWith(arg1, arg2, …) under the alias: .toBeCalledWith() From the source code: https://github.com/facebook/jest/blob/b7cb5221bb06b6fe63c1a5e725ddbc1aaa82d306/packages/expect/src/spyMatchers.ts#L1128 https://github.com/facebook/jest/blob/b7cb5221bb06b6fe63c1a5e725ddbc1aaa82d306/packages/expect/src/spyMatchers.ts#L1131 //… toBeCalledWith: createToBeCalledWithMatcher(‘toBeCalledWith’), toHaveBeenCalled: createToBeCalledMatcher(‘toHaveBeenCalled’), toHaveBeenCalledTimes: createToBeCalledTimesMatcher(‘toHaveBeenCalledTimes’), toHaveBeenCalledWith: createToBeCalledWithMatcher(‘toHaveBeenCalledWith’), //… They are created by the createToBeCalledWithMatcher function with only a different name. So, they are the same. UPDATE: Here is my personal understanding of why jestjs provide these … Read more

Testing two environments with jest

December 4, 2023 by Tarik

EDIT (Jan 2018): It is now possible to do so (since Jest v20), and the option is called projects. Read more about it the docs. Basically you can define an array of your projects you want Jest to be run within: { “projects”: [“<rootDir>/client”, “<rootDir>/server”, “<rootDir>/some-glob/*”] } Just remember every project needs to have its … Read more

Conditionally run tests in Jest

November 30, 2023 by Tarik

const itif = (condition) => condition ? it : it.skip; describe(‘suite name’, () => { itif(true)(‘test name’, async () => { // Your test }); });

Is there a jest config that will fail tests on console.warn?

November 29, 2023 by Tarik

You can use this simple override : let error = console.error console.error = function (message) { error.apply(console, arguments) // keep default behaviour throw (message instanceof Error ? message : new Error(message)) } You can make it available across all tests using Jest setupFiles. In package.json : “jest”: { “setupFiles”: [ “./tests/jest.overrides.js” ] } Then put … Read more

Jest coverage: How can I get a total percentage of coverage?

November 21, 2023 by Tarik

Thanks to Teneff’s answer, I go with the coverageReporter=”json-summary”. jest –coverage –coverageReporters=”json-summary” This generates a coverage-summary.json file which can easily be parsed. I get the total values directly from the json: “total”: { “lines”: { “total”: 21777, “covered”: 65, “skipped”: 0, “pct”: 0.3 }, “statements”: { “total”: 24163, “covered”: 72, “skipped”: 0, “pct”: 0.3 }, … Read more

Eslint jest/globals environment key unknown

September 28, 2023 by Tarik

Follow this guide: https://www.npmjs.com/package/eslint-plugin-jest Basics is: npm i –save-dev eslint-plugin-jest Add this to your .eslintrc file: “plugins”: [“jest”] Then your env property “jest/globals”: true should work.

Configure jest timeout once for all tests

September 5, 2023 by Tarik

Jest offers a testTimeout configuration option you can add to your package.json: “jest”: { “testTimeout”: 15000, }

Jest+React Native Testing Library: How to test an image src?

August 29, 2023 by Tarik

If you’re using @testing-library/react rather than @testing-library/react-native, and you have an alt attribute on your image, you can avoid using getByDataTestId and instead use getByAltText. it(‘uses correct src’, async () => { const { getByAltText } = await render(<MyComponent />); const image = getByAltText(‘the_alt_text’); expect(image.src).toContain(‘the_url’); // or expect(image).toHaveAttribute(‘src’, ‘the_url’) }); Documentation. Unfortunately, it appears that … Read more

How to publish Jest Unit Test Results in VSTS tests?

August 27, 2023 by Tarik

I’ve used a different approach, b/c after some research I found that the Jest testResultsProcessor property is deprecated. I’m using the jest-junit package for test reports (which has been worked on more recently than the jest-trx-results-processor, fwiw): Add jest-junit to package.json Eg yarn add -D jest-junit or npm add –save-dev jest-junit Add a VSTS task … Read more