Not only did it tell us which test failed, it also told us what the expected value would be, which value it received, and what line number this occurred. Making statements based on opinion; back them up with references or personal experience. The "serializes to the same string" error happens in Jest when you try to expect an object to match a certain value, but you are using the wrong matcher. So, in my case the type caused to fail. Well occasionally send you account related emails. You might suggest using toMatchObject. The objects had functions defined and was the reason toMatchObject failed. Web Just had this problem when tried to compare arrays where in one array there was an element with -1 index set imagine any other key to be set except numbers from 0 to N. Serializes to the same string. Thank you for the quick reply. @patran So I can understand the problem in toMatchObject if your test gets an array of objects from MongoDB with mongoose, can you add console.log() for original array and first object: Paste the results after editing to delete properties that are not added by mongoose. When I copy and paste into a local test file, there is syntax error for values of _id properties like 5cfbb57e37912c8ff6d2f8b1 instead of '5cfbb57e37912c8ff6d2f8b1'. So a simple solution would be to convert your arrow functions to normal functions in classes. Extremely helpful @pedrottimark Many thanks Yes, the fact that work-around actually passed totally baffled me. A long-term goal for Jest is to bridge gaps like this between the comparison and the report. All Rights Reserved. It looks like theres something Im not understanding about checking for class object (Deal) equality with functions. In my case I was comparing the array of objects (basically a model class). Check out our interactive course to master JavaScript in less time. And got the error, but was able to resolve that, by wrapping nested array with expect.arrayContaining(['array']) (inside toMatchObject). To fix the "Received: serializes to the same string" error with Jest and JavaScript, we can use the toStrictEqual method. A limit involving the quotient of two sums. Jest : - - - toEqual in jest can compare two object, it is cool (in js we can't compare directly by '=='), but if the object contains an function (like () => {}), it will have problem to compare. Subscribe to our newsletter! Jest throws an error " Received: serializes to the same string", Jest Received: serializes to the same string. SolveForum.com may not be responsible for the answers or solutions given to any question asked by the users. PS. Update toStrictEqual() to be able to check jest.fn().mock.calls etc. Jest says this about, Back when I posted I think the toEqueal method didnt cut it, Ill have a look at it. So I changed the whole test to this: And it passes, and also fails when it should. Specifying a Data Contract Surrogate. Received: serializes to the same string. ERROR: CREATE MATERIALIZED VIEW WITH DATA cannot be executed from a function, Minimising the environmental effects of my dyson brain. It looks like there's something I'm not understanding about checking for class object (Deal) equality with functions. By clicking Sign up for GitHub, you agree to our terms of service and Disclaimer: All information is provided as it is with no warranty of any kind. I ran the same test with both libs at latest versions, Jest 28 and Vitest 0.12.4. Your email address will not be published. For example, you might have one of the following in your test case: In its simplest form (using an empty array or object), this test won't pass. 0. ALL the fields were the same except the entries inside the array coming from Graphql did not have any __proto__ while the ones from my test input had __proto__: Object and that cause the toStrictEqual to fail, because it checks the types besides the structure. This happens because each object reference is different in JavaScript. Even using the "stringify-all-the-things" hack from @manhhailua does not work for me. Questions labeled as solved may be solved or may not be solved depending on the type of question and the date posted for some posts may be scheduled to be deleted periodically. I am also using shallow rendering and experience bad test results. So you may have this error in the following scenario: const arr = [1, 2] arr [-1] = 'foo' expect (arr).toEqual ( [1, 2]) They both serialized to the same string, but they are not equal. How to check whether a string contains a substring in JavaScript? But that is my working test: Have the similar issue with the HTML comparison. We don't spam. // Both of these examples will throw "erializes to the same string", Test throwing "serializes to the same string" error, Using correct matchers for checking object equality. Connect and share knowledge within a single location that is structured and easy to search. I may compare array length, but the information is restricted to a simple number instead the error key diff. [Solved] Jest.js error: "Received: serializes to the same string" Is there a proper earth ground point in this switch box? While instanceof indeed fails (and reading up on vm contexts, necessarily so), examining the proto constructor might offer a solution for all globals, rather than just Array. Well occasionally send you account related emails. To overcome the problem, I used. If you read the error message above, you may already know why. rev2023.3.3.43278. How do I replace all occurrences of a string in JavaScript? Critical issues have been reported with the following SDK versions: com.google.android.gms:play-services-safetynet:17.0.0, Flutter Dart - get localized country name from country code, navigatorState is null when using pushNamed Navigation onGenerateRoutes of GetMaterialPage, Android Sdk manager not found- Flutter doctor error, Flutter Laravel Push Notification without using any third party like(firebase,onesignal..etc), How to change the color of ElevatedButton when entering text in TextField, How to test class instance inside a function with Jest, Jest Test "Compared values have no visual difference.". expected: "test" received: "test". Here is a work-around to get rid of [non-index properties]: users.slice(0) also gets rid of non-index properties. . Jordan's line about intimate parties in The Great Gatsby? The problem is, while comparing it checks for the arrow functions also. I had this same issue with jest. Not the answer you're looking for? In my situation, I was deep equal checking a proxied object vs a regular object. Converting the non-array to something with instanceof Array === true does not help: I'm encountering this with just plain strings. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? That "received" kind of sounds like the test did pass, because what it received serialized to the same string that the expected value serializes to. If you cant convert to normal function you can use JSON.stringify() to convert them first to strings and then use toEqual() or toBe(). What does this exception even mean? Using Kolmogorov complexity to measure difficulty of problems? But I suspect comparing that structure in a code snippet won't work. Questions labeled as solved may be solved or may not be solved depending on the type of question and the date posted for some posts may be scheduled to be deleted periodically. For both these use cases, a default serialization is provided. In my other life, I'm a professional musician, and I fell in love with coding after teaching myself Swift and building an app for audiences at my piano bar gigs. My solution was to mock the module when the function resided before running the test, the mocking ensured that all the functions have the same identity. Most of my work leans toward front end development, but I really enjoy touching all parts of the stack. Quite annoying that we have to look for a workaround every time we need to compare deep nested objects, object methods, etc. My test snippet is below: Use .toMatchObject to check that a JavaScript object matches a subset of the properties of an object. It may not display this or other websites correctly. Already on GitHub? My problem was that we'd put a static property on our array, which is similar to this. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. When I change the matcher to "toContainEqual" is outputs this: (^ a failing test showing that the results are exactly the same. I had this error after introducing a circular dependency while writing tests. Instead, each triggers a completely different response: The recent change to display serializes to the same string makes more obvious when there are inconsistencies between the comparison in the matcher and the feedback in the report. Hi Jonathan, is it possible that you pass a sample of apiProducts in order to reproduce this error? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. So once converted to normal function you can simply use toEqual() for comparison. I specify the jest library version as the response I get may have evolved or is evolving: it('should work', () => { // // Expected: {"hello": "world"} // Received: serializes to the same string expect(hello).toBe( { hello: 'world' }); }); Here the test does not pass even-though the two variables expected looks similar to our value. I tried passing userRef but now getting error Received: serializes to the same string let userRef = { get: () => { return { id: 1, data: () => {}, }; }, }; let expected = { id: 1, data: () => {}, }; expect(generator.next(userRef).value).toEqual(expected); 1 share ReportSave Is there a way to disable "serializes to the same string" so it could resolve positively? We and our partners use data for Personalised ads and content, ad and content measurement, audience insights and product development. I am not sure why the work-around that you found solves the problem :). I had a similar case where the object had a base64 encoded string, I managed the test to compare the serialization of the object using JSON.stringify: Your email address will not be published. Asking for help, clarification, or responding to other answers. There's something strange about the testing environment. It is because Jest probably doesn't resolve nested array automatically in that case. Second, for objects to be persisted. Do not hesitate to share your thoughts here to help others. nSo you may have this error in the following scenario: They both serialized to the same string, but they are not equal. But, sadly: Similarly to other colleagues I had this issue with an Array comparison, I was basically testing a function that got the largest string in an array, additionally it should return an array if more than 1 of those strings matched the largest length possible.
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