I am working on setting up an automation test suite for an application using selenium and jest and it turns out that the console never reaches the inner body of the minimalist test case written below.
describe('When a user Opens Launchpad', () => {
test('It should be able to Navigate to Tasks Application without errors', async () => {
driver.get('http://localhost:4004/fiori.html').then(function () {
const temp = driver.findElement(By.xpath("li[#id='__tile11']"));
temp.then(function (element){
element.getAttribute("innerHTML");
expect(element.getText()).toBe("VT Dashboard");
})
});
}, 200000);
});
I looked online and tried multiple fixes like putting the driver.get() method above all these functions, making the test cases synchronous and using getText() instead of getAttribute() but none of them worked.
I either get an element not found error (The element actually exists when I check it on the chromium browser) or the test case executes successfully without reaching the expect statement in debug mode.
Bottomline is that driver.findElement() returns a promise instead of an element and would be great if I could get an element instead of promise.
Any help or correction here would be greatly appreciated.
If the function is async you should return the promise chain from that function or just use await keyword. So try following:
test('It should be able to Navigate to Tasks Application without errors', async () => {
await driver.get('http://localhost:4004/fiori.html');
const temp = await driver.findElement(By.xpath("li[#id='__tile11']"));
element.getAttribute("innerHTML");
expect(element.getText()).toBe("VT Dashboard");
}, 200000);
or
test('It should be able to Navigate to Tasks Application without errors', async () => {
return driver.get('http://localhost:4004/fiori.html').then(function () {
const temp = driver.findElement(By.xpath("li[#id='__tile11']"));
temp.then(function (element){
element.getAttribute("innerHTML");
expect(element.getText()).toBe("VT Dashboard");
})
});
}, 200000);
I have 2 files with 1 function in it. My test is just as simple, see below:
doc.js
export function createSynthId(doc) {
const synthId = `${doc.attachmentId}-${doc.materialId}-${doc.fileName}-${doc.title}-${doc.materialURL}`;
return synthId;
}
doc.test.js
import { createSynthId } from './doc';
describe('doc', () => {
it('create synthetic id', () => {
expect(createSynthId(global.doc)).toEqual('987654-123456-File Name.pptx-undefined-');
});
it('create synthetic id', () => {
expect(createSynthId({})).toEqual('undefined-undefined-undefined-undefined-undefined');
});
});
My second file is virtually the same, just a larger function. Both tests pass, but coverage is being reported at 0% for Statements, Functions, and Lines, but 100% for Branches. The coverage report is showing all the lines red as well.
We have many similar files and they all work. What am I missing here?
UPDATE
I added a temp function to doc.js
export const makeTestsHappy = () => {
console.log(CONFIG);
};
adding to doc.test.js
it('does more', () => {
makeTestsHappy();
});
and when I try to test that, I get the error TypeError: (0 , _doc.makeTestsHappy) is not a function
Dummy over here was mocking the file I was testing. I forgot to jest.unmock('/doc') It immediately started working when I unlocked. Thanks all for your patience :D
Try to rename your test file from doc.test.js to doc.spec.js. You are using the BDD syntax and the correct name should include spec.
I was trying to mock rejected value and got this error. It's weird that this construction works in the case of "success" addUser.mockImplementation(value => jest.fn().mockResolvedValue(value)), but when I'm trying to do the same trick with rejecting, it doesn't work and says 'Cannot read property 'createEvent' of null'
Here is my test case
it('receives invalid value and throws an error', async () => {
addUser.mockImplementation(() =>
jest.fn().mockRejectedValue(new Error('Sample error'))
)
const enqueueSnackbar = jest.fn()
useSnackbar.mockReturnValue({ enqueueSnackbar })
const { emailInput, form, submitButton } = setup()
await act(async () => {
fillIn(emailInput, 'sample#mail.com')
})
expect(emailInput.value).toBe('sample#mail.com')
expect(submitButton).toHaveProperty('disabled', false)
await act(async () => {
fireEvent.submit(form)
})
expect(enqueueSnackbar).toHaveBeenCalledTimes(1)
expect(enqueueSnackbar).toHaveBeenCalledWith(`Sample error`, {
variant: 'error'
})})
Does anyone know how to make it work?
This seems to be the #1 question that is found when someone Googles "Cannot read property 'createEvent' of null", so leaving this answer here for those readers:
For me this error came in the midst of a test.
When executing a series of tests, some test or the other used to fail with this error, with no indication of where things went wrong. But the answer turned out to be not the test but the component itself:
It was an unmocked API call.
There was an API call being made in a hook and that hook was used in the component with the failing tests. Obviously Jest cleaned up everything after completing its test, and when the call returned, it found nothing so it errored out.
Mocking the hook solved the issue.
If someone comes across such an error, make sure to mock any asynchronous logic you have, especially if it interacts with the DOM when it returns.
Similar to what #alexandre_anicio stated. I was getting this error when using the findAllByText query.
expect(screen.findAllByText('word'))...
When I switched to the getAllByText the error went away and the test passed.
expect(screen.getAllByText('word'))...
If I used expect(await screen.findAllByText('word'))... I noticed the test passed as well.
Digging deeper, this is because findBy tests return a promise so the await is needed. https://testing-library.com/docs/guide-disappearance/#1-using-findby-queries
It would have been nice for the library to throw a better error however.
This seems to work for me but I can't explain it. Try removing your act() wrapper, and use await immediately after calling the fireEvent function.
fireEvent.submit(form);
await wait();
When I encountered this same error message, I discovered I had forgotten to declare my test function as async after I updated the expectation to include await.
waitFor already uses act under the hood so there's no need to use the act blocks there.
I recognize the error you mentioned but the way I replicate it is using waitFor without await, something like this:
it('works', async() => {
render(<SomeComponent />);
// (some setup here)
waitFor(() => { // notice that we are not awaiting this promise
expect(someChange).toBeInTheDocument();
});
});
Could you try
it('receives invalid value and throws an error', async () => {
addUser.mockImplementation(() =>
jest.fn().mockRejectedValue(new Error('Sample error'))
)
const enqueueSnackbar = jest.fn()
useSnackbar.mockReturnValue({ enqueueSnackbar })
const { emailInput, form, submitButton } = setup()
fillIn(emailInput, 'sample#mail.com') // This is using some fireEvent under the hood right?
await waitFor(() => {
expect(emailInput.value).toBe('sample#mail.com')
expect(submitButton).toHaveProperty('disabled', false)
});
fireEvent.submit(form)
await waitFor(() => {
expect(enqueueSnackbar).toHaveBeenCalledTimes(1)
expect(enqueueSnackbar).toHaveBeenCalledWith(`Sample error`, {
variant: 'error'
})
});
})
Similar issue and error messages, adding await before userEvent did the trick
Before
userEvent.upload(screen.getByRole('button'), ...)
userEvent.upload(screen.getByLabelText('Upload'), FILE)
After
await userEvent.upload(screen.getByRole('button'), ...)
await userEvent.upload(screen.getByLabelText('Upload'), FILE)
I had some problems using mockImplementation(() => Promise) (returning some promise) and the await waitFor(()=> ...) at the same time.
If you are using react-testing-library, you can work around this problem using findBy query, that are a combination of getBy queries and waitFor. The only downside is that you have to find something visual (a text, data-test-id, label, etc...) that can tell you that the mock function have been called. On your code you can try something like this:
it('receives invalid value and throws an error', async () => {
addUser.mockImplementation(() =>
jest.fn().mockRejectedValue(new Error('Sample error'))
)
await screen.findByText('Sample Error message reflected in your component')
... rest of your tests ...
})
1. await waitFor(() => expect(history.location.pathname).toBe('/auth'))
2. await waitFor(() => expect(history.location.pathname)).toBe('/auth')
It's about something else but the same error. Spent 2 hours so you don't have to :)
The second one with the parenthesis in the wrong place was the culprit
I was getting
/…/node_modules/.pnpm/react-dom#17.0.2_react#17.0.2/node_modules/react-dom/cjs/react-dom.development.js:3905
var evt = document.createEvent('Event');
^
TypeError: Cannot read property 'createEvent' of null
at Object.invokeGuardedCallbackDev (/…/node_modules/.pnpm/react-dom#17.0.2_react#17.0.2/node_modules/react-dom/cjs/react-dom.development.js:3905:26)
at invokeGuardedCallback (/…/node_modules/.pnpm/react-dom#17.0.2_react#17.0.2/node_modules/react-dom/cjs/react-dom.development.js:4056:31)
at flushPassiveEffectsImpl (/…/node_modules/.pnpm/react-dom#17.0.2_react#17.0.2/node_modules/react-dom/cjs/react-dom.development.js:23543:11)
at unstable_runWithPriority (/…/node_modules/.pnpm/scheduler#0.20.2/node_modules/scheduler/cjs/scheduler.development.js:468:12)
at runWithPriority$1 (/…/node_modules/.pnpm/react-dom#17.0.2_react#17.0.2/node_modules/react-dom/cjs/react-dom.development.js:11276:10)
at flushPassiveEffects (/…/node_modules/.pnpm/react-dom#17.0.2_react#17.0.2/node_modules/react-dom/cjs/react-dom.development.js:23447:14)
at Object.<anonymous>.flushWork (/…/node_modules/.pnpm/react-dom#17.0.2_react#17.0.2/node_modules/react-dom/cjs/react-dom-test-utils.development.js:992:10)
at Immediate.<anonymous> (/…/node_modules/.pnpm/react-dom#17.0.2_react#17.0.2/node_modules/react-dom/cjs/react-dom-test-utils.development.js:1003:11)
at processImmediate (internal/timers.js:461:21)
Tracked down to an import statement.
I was able to "fix" it by changing:
import { AddCircle, RemoveCircle } from '#mui/icons-material';
to
import AddCircle from '#mui/icons-material/AddCircle';
import RemoveCircle from '#mui/icons-material/RemoveCircle';
Crazy.
If the error is because of wrong usage of jest's findBy* instead of async/await you can also return promise:
it('test', () => {
expect.assertions(1);
return screen
.findByTestId('iiError')
.then(elem =>
expect(elem).toHaveTextContent(
"This is error message"
)
);
});
Do not forget about expect.assertions and return!
Ref: https://jestjs.io/docs/tutorial-async
I had the same issue, the culprit in my case was that the rendered React component was unmounted with .unmount(). A running API call triggered a callback and React tried to update the DOM, that was already unmounted.
Since this is the top result on Google for this issue, I'll add my own answer. For me, this issue was happening on Circle CI when my tests were running. The Circle CI server ran the tests more slowly because it's CPU is limited, so a long-running test with lots of userEvent.types in it was exceeding the default timeout of 5 seconds.
I don't know why it didn't give an error about exceeding the timeout, but this thread helped me track it down.
All I had to do was increase the timeout on the long-running test.
Error occurred for me because I had work scheduled from useEffect that resolved after the rest was torn down.
The solution is to await Promise.sleep() after each test.
I was facing the same issue
It had to something with the async function not completing before the test case completes
I solved this using await flushMicrotasksQueue()
in my code
I'm trying to run the tests on this promises but I get this error:
"Error: Timeout of 2000ms exceeded. For async tests and hooks, ensure" done () "is called; if returning to Promise, ensure it resolves. (C:\Users\Ranieri\Documents\Projetos\Node Js\testestest\test\libs\registerUser.test.js)"
I have already increased the timeout time but it still does not solve the problem.
I searched for asynchronous test here on stackoverflow and found nothing or anyone with something similar
my test code https://github.com/ran-j/teste
Already tried :
expect(Promise.resolve( userPromesie.selectUser(rUser) ) ).to.be.null
return expect(Promise.resolve( userPromesie.selectUser(rUser) ) ).to.be.null
userPromesie.selectUser(rUser).then((result) => result.to.be.null
selectUser returns a Promise and you need to wait for this to resolve in order to be able to assert against it. This can achieved two ways:
Using then on the returning promise, calling the done() function within that block.
Using async/await, you declare your function async and you await the Promise
Below is an example of an async/await method:
it('should do something with the user', async () => {
const user = await userPromise.selectUser(rUser);
expect(user).to.be.null;
});
I'd highly recommend reading up on Promises for more information: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise
EDIT Here's an example using the done method:
it('should do something with the user', (done) => {
userPromise.selectUser(rUser).then((user) => {
expect(user).to.be.null;
done();
});
});
I want run a bunch of tests on the results obtained from a promise call. I know it can be done as:
it ('should pass test foo1', () => {
return promisecall()
.then(result => {
expect(result.length).to.equal(42)
expect(some other test on data)
expect(some other test on data)
.
.
})
})
According to my understanding, what this does is:
Runs a single test (i.e should pass test foo1) which passes only if all the expect conditions are true, and these expect parts will not show in the output screen.
How can I add multiple 'it' / unit tests on the results of a single promise result, so that the different test cases actually show up in the output?
You should be able to group them together in a describe() and run the promise in a before():
describe('things with promises', () => {
var promiseResult;
before(() => promiseCall().then(result => promiseResult = result));
it ('should pass test foo1', () => expect(promiseResult.length).to.equal(42));
it ('should pass test foo2', () => expect(some other test));
// ...
});