It is the inverse of expect.stringMatching. You can write: If you have a mock function, you can use .nthCalledWith to test what arguments it was nth called with. This is especially useful for checking arrays or strings size. A sequence of dice rolls', 'matches even with an unexpected number 7', 'does not match without an expected number 2', 'onPress gets called with the right thing', // affects expect(value).toMatchSnapshot() assertions in the test file, 'does not drink something octopus-flavoured', 'registration applies correctly to orange La Croix', 'applying to all flavors does mango last', // Object containing house features to be tested, // Deep referencing using an array containing the keyPath, 'drinking La Croix does not lead to errors', 'drinking La Croix leads to having thirst info', 'the best drink for octopus flavor is undefined', 'the number of elements must match exactly', '.toMatchObject is called for each elements, so extra object properties are okay', // Test that the error message says "yuck" somewhere: these are equivalent, // Test that we get a DisgustingFlavorError. For example, let's say you have a drinkAll(drink, flavour) function that takes a drink function and applies it to all available beverages. Book about a good dark lord, think "not Sauron". Verify that when we click on the Card, the analytics and the webView are called. For example, this code tests that the promise resolves and that the resulting value is 'lemon': Since you are still testing promises, the test is still asynchronous. We spied on components B and C and checked if they were called with the right parameters only once. This keeps all the mock modules and implementations close to the test files, making it easy to understand the relationship between the mocked modules and the tests that use them. For testing the items in the array, this matcher recursively checks the equality of all fields, rather than checking for object identity. For example, if getAllFlavors() returns an array of flavors and you want to be sure that lime is in there, you can write: Use .toContainEqual when you want to check that an item with a specific structure and values is contained in an array. What tool to use for the online analogue of "writing lecture notes on a blackboard"? The expect function is used every time you want to test a value. For more insightsvisit our website: https://il.att.com, Software developer, a public speaker, tech-blogger, and mentor. For example, let's say you have a drinkEach(drink, Array) function that applies f to a bunch of flavors, and you want to ensure that when you call it, the first flavor it operates on is 'lemon' and the second one is 'octopus'. Use .toBeTruthy when you don't care what a value is and you want to ensure a value is true in a boolean context. 8 comments twelve17 commented on Apr 26, 2019 edited 24.6.0 Needs Repro Needs Triage on Apr 26, 2019 changed the title null as a value null as a value on Apr 26, 2019 on Apr 26, 2019 To subscribe to this RSS feed, copy and paste this URL into your RSS reader. You should invoke it before you do the assertion. Use .toBeNaN when checking a value is NaN. For example, let's say you have some application code that looks like: You may not care what getErrors returns, specifically - it might return false, null, or 0, and your code would still work. For example, test that ouncesPerCan() returns a value of at least 12 ounces: Use toBeLessThan to compare received < expected for numbers. It is the inverse of expect.stringContaining. This issue has been automatically locked since there has not been any recent activity after it was closed. For example, let's say you have a drinkAll (drink, flavour) function that takes a drink function and applies it to all available beverages. You could abstract that into a toBeWithinRange matcher: In TypeScript, when using @types/jest for example, you can declare the new toBeWithinRange matcher in the imported module like this: If you want to move the typings to a separate file (e.g. So if you want to test that thirstInfo will be truthy after drinking some La Croix, you could write: Use .toBeUndefined to check that a variable is undefined. If you want to check that console.log received the right parameter (the one that you passed in) you should check mock of your jest.fn(). RV coach and starter batteries connect negative to chassis; how does energy from either batteries' + terminal know which battery to flow back to? Use test-specific data: Avoid using real data from your application in tests. Usually jest tries to match every snapshot that is expected in a test. To use snapshot testing inside of your custom matcher you can import jest-snapshot and use it from within your matcher. rev2023.3.1.43269. For example, due to rounding, in JavaScript 0.2 + 0.1 is not strictly equal to 0.3. It is recommended to use the .toThrow matcher for testing against errors. As we can see, the two tests were created under one describe block, Check onPress, because they are in the same scope. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Issues without a reproduction link are likely to stall. If you mix them up, your tests will still work, but the error messages on failing tests will look strange. The following example contains a houseForSale object with nested properties. In TypeScript, when using @types/jest for example, you can declare the new toBeWithinRange matcher in the imported module like this: expect.extend({ toBeWithinRange(received, floor, ceiling) { // . Use .toHaveReturnedWith to ensure that a mock function returned a specific value. If you have a mock function, you can use .toHaveReturned to test that the mock function successfully returned (i.e., did not throw an error) at least one time. In this article, we will discuss a few best practices that I find useful for unit testing React Native applications using the React Native Testing Library (RNTL) and Jest. I am trying to mock third part npm "request" and executed my test cases, but i am receiving and the test fails. Where is the invocation of your function inside the test? This matcher uses instanceof underneath. Does Cosmic Background radiation transmit heat? Generally you need to use one of two approaches here: 1) Where the click handler calls a function passed as a prop, e.g. You can call expect.addSnapshotSerializer to add a module that formats application-specific data structures. The optional numDigits argument limits the number of digits to check after the decimal point. For example, this code tests that the best La Croix flavor is not coconut: Use resolves to unwrap the value of a fulfilled promise so any other matcher can be chained. You can provide an optional propertyMatchers object argument, which has asymmetric matchers as values of a subset of expected properties, if the received value will be an object instance. You can use it inside toEqual or toBeCalledWith instead of a literal value. If you know how to test something, .not lets you test its opposite. You might want to check that drink function was called exact number of times. You also have to invoke your log function, otherwise console.log is never invoked: it ('console.log the text "hello"', () => { console.log = jest.fn (); log ('hello'); // The first argument of the first call . This approach keeps the test files close to the component files, making it easy to find and maintain them by identifying which test corresponds to which component. Use .toBeFalsy when you don't care what a value is and you want to ensure a value is false in a boolean context. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. .toBeNull() is the same as .toBe(null) but the error messages are a bit nicer. You make the dependency explicit instead of implicit. expect.arrayContaining (array) matches a received array which contains all of the elements in the expected array. This method requires a shallow/render/mount instance of a React.Component to be available. Here is an example of using a functional component. Nonetheless, I recommend that you try new strategies yourself and see what best suits your project. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. So use .toBeNull() when you want to check that something is null. Why does Jesus turn to the Father to forgive in Luke 23:34? A common location for the __mocks__ folder is inside the __tests__ folder. Well occasionally send you account related emails. For null this should definitely not happen though, if you're sure that it does happen for you please provide a repro for that. When you're writing tests, you often need to check that values meet certain conditions. How do I check if an element is hidden in jQuery? While it does not answer the original question, it still provides insight on other techniques that could suit cases indirectly related to the question. expect.anything() matches anything but null or undefined. Therefore, it matches a received array which contains elements that are not in the expected array. expect.anything() matches anything but null or undefined. To learn more, see our tips on writing great answers. Any idea why this works when we force update :O. On Jest 15: testing toHaveBeenCalledWith with 0 arguments passes when a spy is called with 0 arguments. To learn more, see our tips on writing great answers. How do I check for an empty/undefined/null string in JavaScript? Therefore, it matches a received array which contains elements that are not in the expected array. Essentially spyOn is just looking for something to hijack and shove into a jest.fn(). How can I make this regulator output 2.8 V or 1.5 V? The App.prototype bit on the first line there are what you needed to make things work. You can use it instead of a literal value: expect.assertions(number) verifies that a certain number of assertions are called during a test. For example, let's say you have a drinkEach(drink, Array) function that takes a drink function and applies it to array of passed beverages. Keep tests organized: Group tests by related functionality and consider using a pattern such as test description for the test names and each loop on the data. For example, you might not know what exactly essayOnTheBestFlavor() returns, but you know it's a really long string, and the substring grapefruit should be in there somewhere. Instead of literal property values in the expected object, you can use matchers, expect.anything(), and so on. 1. For example, let's say that we expect an onPress function to be called with an Event object, and all we need to verify is that the event has event.x and event.y properties. Use .toBeDefined to check that a variable is not undefined. How do I test for an empty JavaScript object? The solution mockInstead of testing component B elements when testing component A, we spy/mock component B. For example, this test fails: It fails because in JavaScript, 0.2 + 0.1 is actually 0.30000000000000004. Use .toHaveLength to check that an object has a .length property and it is set to a certain numeric value. It will match received objects with properties that are not in the expected object. You would be spying on function props passed into your functional component and testing the invocation of those. For edge cases, we will check if our values can be null or undefined without causing the app to crash. The open-source game engine youve been waiting for: Godot (Ep. React For an individual test file, an added module precedes any modules from snapshotSerializers configuration, which precede the default snapshot serializers for built-in JavaScript types and for React elements. The root describe will always be called with the name of the component -. The argument to expect should be the value that your code produces, and any argument to the matcher should be the correct value. And when pass is true, message should return the error message for when expect(x).not.yourMatcher() fails. http://airbnb.io/enzyme/docs/api/ShallowWrapper/instance.html, The open-source game engine youve been waiting for: Godot (Ep. Use .toHaveReturnedTimes to ensure that a mock function returned successfully (i.e., did not throw an error) an exact number of times. jest enzyme, Jest onSpy does not recognize React component function, Jest/Enzyme Class Component testing with React Suspense and React.lazy child component, How to use jest.spyOn with React function component using Typescript, Find a vector in the null space of a large dense matrix, where elements in the matrix are not directly accessible, Ackermann Function without Recursion or Stack. pass indicates whether there was a match or not, and message provides a function with no arguments that returns an error message in case of failure. Intuitive equality comparisons often fail, because arithmetic on decimal (base 10) values often have rounding errors in limited precision binary (base 2) representation. A great way to do this is using the test.each function to avoid duplicating code. By clicking Sign up for GitHub, you agree to our terms of service and 5. Use toBeGreaterThan to compare received > expected for numbers. We are using toHaveProperty to check for the existence and values of various properties in the object. Is email scraping still a thing for spammers, Incomplete \ifodd; all text was ignored after line. expect.hasAssertions() verifies that at least one assertion is called during a test. For example, test that ouncesPerCan() returns a value of at most 12 ounces: Use .toBeInstanceOf(Class) to check that an object is an instance of a class. After that year, we started using the RNTL, which we found to be easier to work with and more stable. Can non-Muslims ride the Haramain high-speed train in Saudi Arabia? It is like toMatchObject with flexible criteria for a subset of properties, followed by a snapshot test as exact criteria for the rest of the properties. For testing the items in the array, this uses ===, a strict equality check. We create our own practices to suit our needs. We can do that with: expect.stringContaining(string) matches the received value if it is a string that contains the exact expected string. Use .toThrow to test that a function throws when it is called. For example, to assert whether or not elements are the same instance: Use .toHaveBeenCalledWith to ensure that a mock function was called with specific arguments. expect.objectContaining(object) matches any received object that recursively matches the expected properties. Use .toBe to compare primitive values or to check referential identity of object instances. For testing the items in the array, this uses ===, a strict equality check. Everything else is truthy. Another option is to use jest.spyOn (instead of replacing the console.log it will create a proxy to it): Another option is to save off a reference to the original log, replace with a jest mock for each test, and restore after all the tests have finished. As it is a breaking change to change the default behaviour, is it possible to have another matcher of toHaveBeenCalledWith that could do the strict equals behaviour? For example, let's say that we have a few functions that all deal with state. You can use expect.extend to add your own matchers to Jest. For testing the items in the array, this matcher recursively checks the equality of all fields, rather than checking for object identity. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. The text was updated successfully, but these errors were encountered: I believe this is because CalledWith uses toEqual logic and not toStrictEqual. For checking deeply nested properties in an object you may use dot notation or an array containing the keyPath for deep references. If the promise is rejected the assertion fails. Strange.. is there a chinese version of ex. How do I remove a property from a JavaScript object? For example, if you want to check that a function bestDrinkForFlavor(flavor) returns undefined for the 'octopus' flavor, because there is no good octopus-flavored drink: You could write expect(bestDrinkForFlavor('octopus')).toBe(undefined), but it's better practice to avoid referring to undefined directly in your code. To learn more, see our tips on writing great answers. 542), How Intuit democratizes AI development across teams through reusability, We've added a "Necessary cookies only" option to the cookie consent popup. If you want to check the side effects of your myClickFn you can just invoke it in a separate test. You can write: Also under the alias: .lastReturnedWith(value). When you're writing tests, you often need to check that values meet certain conditions. Feel free to share in the comments below. The full example repository is at github.com/HugoDF/jest-specific-argument-assert, more specifically lines 17-66 in the src/pinger.test.js file. Let's say you have a method bestLaCroixFlavor() which is supposed to return the string 'grapefruit'. Use .toEqual to compare recursively all properties of object instances (also known as "deep" equality). Is there a standard function to check for null, undefined, or blank variables in JavaScript? If you have a mock function, you can use .toHaveBeenNthCalledWith to test what arguments it was nth called with. If you have floating point numbers, try .toBeCloseTo instead. We recommend using StackOverflow or our discord channel for questions. For your particular question, you just needed to spy on the App.prototype method myClickFn. For example, let's say you have a mock drink that returns true. You can provide an optional hint string argument that is appended to the test name. expect gives you access to a number of "matchers" that let you validate different things. You mean the behaviour from toStrictEqual right? For example, if you want to check that a mock function is called with a number: expect.arrayContaining(array) matches a received array which contains all of the elements in the expected array. The last module added is the first module tested. Already on GitHub? Kt Lun. expect.arrayContaining (array) matches a received array which contains all of the elements in the expected array. Sign in @Byrd I'm not sure what you mean. Docs: For example, this code tests that the promise rejects with reason 'octopus': Alternatively, you can use async/await in combination with .rejects. jest.toHaveBeenCalledWith (): asserting on parameter/arguments for call (s) Given the following application code which has a counter to which we can add arbitrary values, we'll inject the counter into another function and assert on the counter.add calls. So what *is* the Latin word for chocolate? This is useful if you want to check that two arrays match in their number of elements, as opposed to arrayContaining, which allows for extra elements in the received array. You can also pass an array of objects, in which case the method will return true only if each object in the received array matches (in the toMatchObject sense described above) the corresponding object in the expected array. In that case you can implement a custom snapshot matcher that throws on the first mismatch instead of collecting every mismatch. @twelve17 in addition to what Tim said in preceding comment, study your example code to see: If you make some assumptions about number of calls, you can write specific assertions: Closing as it appears to be intended behavior. If differences between properties do not help you to understand why a test fails, especially if the report is large, then you might move the comparison into the expect function. .toHaveBeenCalled () Also under the alias: .toBeCalled () Use .toHaveBeenCalled to ensure that a mock function got called. Therefore, it matches a received object which contains properties that are present in the expected object. Here's how you would test that: In this case, toBe is the matcher function. I am trying to mock third part npm "request" and executed my test cases, but i am receiving and the test fails expect (jest.fn ()).toHaveBeenCalledWith (.expected) Expected: 200 Number of calls: 0 The following is my code: spec.js Function mock using jest.fn () The simplest and most common way of creating a mock is jest.fn () method. I'm still not fully convinced though since I don't think it's jest's job to be a linter, and taking a step back, I think it makes sense for the test to pass in this scenario. I guess the concern would be jest saying that a test passed when required parameters weren't actually supplied. This has a slight benefit to not polluting the test output and still being able to use the original log method for debugging purposes. expect.hasAssertions() verifies that at least one assertion is called during a test. Use .toContain when you want to check that an item is in an array. You can write: Also under the alias: .nthCalledWith(nthCall, arg1, arg2, ). This example also shows how you can nest multiple asymmetric matchers, with expect.stringMatching inside the expect.arrayContaining. Can I use a vintage derailleur adapter claw on a modern derailleur. How to get the closed form solution from DSolve[]? Thanks for contributing an answer to Stack Overflow! Therefore, it matches a received object which contains properties that are not in the expected object. It calls Object.is to compare primitive values, which is even better for testing than === strict equality operator. Feel free to open a separate issue for an expect.equal feature request. types/jest/index.d.ts), you may need to an export, e.g. They are just syntax sugar to inspect the mock property directly. So use .toBeNull() when you want to check that something is null. Check out the Snapshot Testing guide for more information. Alternatively, you can use async/await in combination with .resolves: Use .rejects to unwrap the reason of a rejected promise so any other matcher can be chained. Let's say you have a method bestLaCroixFlavor() which is supposed to return the string 'grapefruit'. We are using toHaveProperty to check for the existence and values of various properties in the object. Alternatively, you can use async/await in combination with .resolves: Use .rejects to unwrap the reason of a rejected promise so any other matcher can be chained. This ensures the test is reliable and repeatable. How to derive the state of a qubit after a partial measurement? You can use it inside toEqual or toBeCalledWith instead of a literal value. Unit testing is an essential aspect of software development. The argument to expect should be the value that your code produces, and any argument to the matcher should be the correct value. For example, when you make snapshots of a state-machine after various transitions you can abort the test once one transition produced the wrong state. For the default value 2, the test criterion is Math.abs(expected - received) < 0.005 (that is, 10 ** -2 / 2). Works as a mobile developer with React Native at @AT&T, Advanced Data Fetching Technique in React for Senior Engineers, 10 Most Important Mistakes to Avoid When Developing React Native Apps. For example, due to rounding, in JavaScript 0.2 + 0.1 is not strictly equal to 0.3. Launching the CI/CD and R Collectives and community editing features for How do I test a class that has private methods, fields or inner classes? You can match properties against values or against matchers. There are a number of helpful tools exposed on this.utils primarily consisting of the exports from jest-matcher-utils. `` writing lecture notes on a modern derailleur you have a mock function got called required weren! Matches the expected object your matcher say you have a mock function you. Terms of service and 5 the same as.toBe ( null ) but the error for. It fails because in JavaScript let 's say that we have a method (..., with expect.stringMatching inside the __tests__ folder uses toEqual logic and not toStrictEqual use.toHaveBeenNthCalledWith to that... Javascript object you may use dot notation or an array this.utils primarily consisting of the exports from jest-matcher-utils contains! A number of times actually 0.30000000000000004 before you do the assertion Luke 23:34 actually.... A vintage derailleur adapter claw on a blackboard '' arguments passes when a spy is called jest:. Notation or an array we spied on components B and C and checked if they were called with arguments. Jesus jest tohavebeencalledwith undefined to the matcher should be the value that your code produces, any! Test passed when required parameters weren & # x27 ; t actually.!, or blank variables in JavaScript root describe will always be called with 0 arguments the right parameters only.... Waiting for: Godot ( Ep strange.. is there a standard to! When testing component a, we spy/mock component B if an element is hidden in jQuery book about a dark... Clicking sign up for a free GitHub account to open a separate.! Data from your application in tests partial measurement instead of collecting every.... Private knowledge with coworkers, Reach developers & technologists share private knowledge with coworkers, Reach developers technologists... Works when we force update: O you might want to ensure that function. We click on the first module tested object that recursively matches jest tohavebeencalledwith undefined expected properties just looking for to! Testing is an essential aspect of Software development compare received > expected for numbers returned a specific.... After it was nth called with & technologists worldwide.not lets you test its opposite tests will look.! Object that recursively matches the expected array existence and values of various properties in the,. Functions that all deal with state to get the closed form solution from DSolve ]. Let you validate different things feature request empty JavaScript object test for an empty/undefined/null string in JavaScript +. Can write: Also under the alias:.toBeCalled ( ) when you do the assertion on failing will. Edge cases, we will check if an element is hidden in jQuery than checking for identity... Use dot notation or an array containing the keyPath for deep references uses ===, a public,... A value is false in a test passed when required parameters weren & x27. Open an issue and contact its maintainers and the webView are called object contains... Are a bit nicer to expect should be the correct value when it is recommended to use snapshot inside! Is null error messages on failing tests will look strange into your functional component jest tohavebeencalledwith undefined. Strings size guess the concern would be jest saying that a mock function returned a specific value property from JavaScript.:.nthCalledWith ( nthCall, arg1, arg2, ) present in the array, this test fails: fails!.Tobecalled ( ) which is even better for testing the items in the expected properties add your own matchers jest! 'Grapefruit ' ignored after line that formats application-specific data structures ) verifies that at least one assertion is with... How you can use.toHaveBeenNthCalledWith to test that: in this case, toBe is the matcher.! Meet certain conditions property from a JavaScript object object, you agree to our terms of service 5! Tips on writing great answers or blank variables in JavaScript, 0.2 + 0.1 is actually jest tohavebeencalledwith undefined..Tocontain when you want to ensure that a variable is not strictly equal to 0.3 to!, and mentor is inside the __tests__ folder elements in the expected array easier work! From DSolve [ ] in the array, this uses ===, strict. To compare primitive values or against matchers in jQuery use dot notation or an array containing keyPath! After it was nth called with return the string 'grapefruit ' for example, let 's say you a... A functional component React.Component to be available limits the number of helpful exposed... Have a method bestLaCroixFlavor ( ) use.tohavebeencalled to ensure that a mock function returned a specific.. [ ] use.toBe to compare received > expected for numbers modern derailleur be null undefined. The number of times expect.objectcontaining ( object ) matches a received array which contains that... Of `` matchers '' that let you validate different things using StackOverflow or our channel., we will check if our values can be null or undefined, try.toBeCloseTo instead causing the to! '' that let you validate different things of various properties in an object you may use dot notation or array. Array which contains elements that are not in the object method myClickFn been any recent activity after was! And shove into a jest.fn ( ) when you do n't care a. Known as `` deep '' equality ) what you needed to make things work to jest use.toBeFalsy when 're. Are just syntax sugar to inspect the mock property directly compare received > expected for numbers you might want check. Instance jest tohavebeencalledwith undefined a qubit after a partial measurement testing guide for more insightsvisit our website https. Custom matcher you can use.toHaveBeenNthCalledWith to test that a mock function, you often need to an export e.g. Why this works when we click on the first line there are a number of digits check. [ ] on the App.prototype bit on the first line there are you. Test passed when required parameters weren & # x27 ; t actually supplied object has a slight benefit to polluting! So what * is * the Latin word for chocolate.tohavebeencalled ( ) you. These errors were encountered: I believe this is especially useful for checking deeply nested properties snapshot... Add a module that formats application-specific data structures an element is hidden in jQuery error message for when expect x! Time you want to check that an item is in an object has a.length property and it set. Remove a property from a JavaScript object checking for object identity last module added is first! Speaker, tech-blogger, and mentor in a boolean context after a partial measurement array... Match properties against values or to check the side effects of your function inside the expect.arraycontaining checking. What * is * the Latin word for chocolate.toThrow to test something,.not lets you test its.... And checked if they were called with the right parameters only once without causing app... Were encountered: I believe this is using the test.each function to Avoid duplicating code of. When a spy is called with tagged, where developers & technologists share private knowledge with coworkers, developers. The open-source game engine youve been waiting for: Godot ( Ep of to. Latin word for chocolate use it from within your matcher use.toHaveReturnedWith to that! Real data from your application in tests a public speaker, tech-blogger, any. Undefined without causing the app to crash that returns true can write: Also under the alias:.toBeCalled )... Against matchers all deal with state discord channel for questions is recommended to use snapshot testing guide for insightsvisit... Snapshot that is expected in a separate issue for an empty JavaScript object function... Of the elements in the expected array meet certain conditions a property from JavaScript! Numdigits argument limits the number of `` writing lecture notes on a modern derailleur chinese... First mismatch instead of a literal value for edge cases, we spy/mock component B elements when testing component elements... Where is the same as.toBe ( null ) but the error messages on failing tests will still work but... Version of ex how can I make this regulator output 2.8 V or 1.5 V produces, any! Polluting the test output and still being able to use for the existence and values of various properties in array. Than === strict equality check of Software development is and you want check!.Length property and it is set to a number of `` writing lecture notes on a modern.... Recursively all properties of object instances arguments it was nth called with ) Also under the alias.nthCalledWith! Of service and 5 a shallow/render/mount instance of a literal value the.... === strict equality check the RNTL, which we found to be available src/pinger.test.js file were. B and C and checked if they were called with 0 arguments ( array matches. Reach developers & technologists share jest tohavebeencalledwith undefined knowledge with coworkers, Reach developers technologists. Best suits your project use snapshot testing inside of your custom matcher you can use to! To our terms of service and 5 the closed form solution from DSolve [ ] ( )... Was called exact number of times partial measurement book about a good dark lord, ``. Hint string argument that is appended to the Father to forgive in 23:34! Remove a property from a JavaScript object.toThrow matcher for testing the items in the,! To Avoid duplicating code qubit after a partial measurement verifies that at least assertion! Your matcher yourself and see what best suits your project causing the app crash... Were called with repository is at github.com/HugoDF/jest-specific-argument-assert, more specifically lines 17-66 in the,..., arg1, arg2, ) edge cases, we spy/mock component B shove into a jest.fn ( ) is... You would test that: in this case, toBe is the first line there are you! Tools exposed on this.utils primarily consisting of the elements in the expected object of helpful exposed!