What methods can be used to check for incorrect type of a function argument in ts-jest?

I have been experimenting with a TypeScript function lately. To speed up my testing process, I decided to utilize ts-jest.

However, I stumbled upon an issue that seems tricky to resolve. Despite exploring various ts-jest options, I couldn't find a solution. The function only accepts string input.

function tsFunc(arg:string){
  if (typeof(arg)!=='string'){ 
    throw new TypeError('....')
  } 
}

Unfortunately, I am unable to perform tests as calling tsFunc(5) won't compile in the test files.

Any suggestions on how to tackle this challenge?

typescript

Answer №1

If you have a need to test arguments that go against the type contract of the function, then casting the argument to any is a way to inform Typescript to skip type checking on that specific variable.

expect(() => {
  tsFunc(123 as any);
}).toThrow();

Alternatively, you can include a // @ts-expect-error comment.

expect(() => {
  // @ts-expect-error testing incorrect argument type
  tsFunc(123);
}).toThrow();

The choice between these methods is yours. The key is to communicate to Typescript that you are intentionally breaking the rules for testing purposes.

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

I'm having trouble with Angular pipes in certain areas... but I must say, Stackblitz is truly incredible

Encountering this issue: ERROR in src\app\shopping-cart-summary\shopping-cart-summary.component.html(15,42): : Property '$' does not exist on type 'ShoppingCartSummaryComponent'. The error disappears when I remove the c ...

angulartypescriptasync-awaitpipe

How can I convert duplicate code into a function in JavaScript?

I have successfully bound values to a view in my code, but I am concerned about the duplicate nested forEach loops that are currently present. I anticipate that Sonarcube will flag this as redundant code. Can anyone advise me on how to refactor this to avo ...

javascripttypescript

Issue with displaying selected value and options in Mat-select when using formarray - Reactive forms in Angular

I've been working on the code below to create dropdowns, but I'm having trouble getting the selected value and options to show up in the dropdowns. Can you help me figure out what's wrong with the code? Component code testForm: FormGroup; ...

javascriptangulartypescriptangular-reactive-formsangular-forms

Utilizing a service within NestJS

I'm currently in the process of updating some older code and I have created a service that I want to inject into the constructor of a class. There are two key points to consider about this particular class. The first point is that it is instantiated b ...

typescriptnestjs

Ways to assign a random color to every card displayed in a screenshot in Angular 6?

[![enter image description here][1]][1] This is the HTML component code: <div class="row"> <div class="col-lg-3 col-md-3 col-sm-6 col-12"> <a href="javascript:void(0)" (click)="openModal()"> <div class="card card-box HYT ...

angulartypescriptparse-server

Should we utilize the component @Input as a parameter for the injected service constructor, or should we opt for the ServiceFactory

Within Angular 12 lies a simplified component structured as follows: @Component({ selector: 'app-list', templateUrl: './list.component.html', styleUrls: ['./list.component.less'] }) export class ListComponent implements ...

angulartypescript

Webpack is failing to recognize certain CSS files

My development stack includes Vue.js 2.5.15, Webpack 4.12.0, css-loader 0.28.11, ASP.Net Core 2.1 in Visual Studio 2017. Starting with the Visual Studio asp.net core template project for Vue and Typescript, I prefer to have individual small CSS files with ...

csstypescriptwebpackvue.jscss-loader

Guide to updating the file name while downloading in JHipster (Java and Angular)

Here is the snippet of code responsible for opening the file from the controller: openFile(contentType, field) { return this.dataUtils.openFile(contentType, field); } Within the HTML, this function is used to pass in data retrieved from a servic ...

angulartypescriptjhipster

What is the accurate type of control parameter in Typescript?

Recently, I developed a TypeScript React component called FormInput to use in my form. This component integrates the MUI framework and react-hook-form. However, I encountered an issue while trying to set the correct type for the "control" parameter in my c ...

reactjstypescriptmaterial-uireact-hook-form

Discover the most helpful keyboard shortcuts for Next.js 13!

If you're working with a standard Next.js 13 app that doesn't have the experimental app directory, setting up keyboard shortcuts can be done like this: import { useCallback, useEffect } from 'react'; export default function App() { c ...

javascriptreactjstypescriptnext.js

Discovering the JavaScript source file for a package using WebStorm and TypeScript

In my TypeScript project, there is a usage of Express with the following method: response.send('Hello'); I am interested in exploring the implementation of the send() method. However, when I try to navigate to the source code by ctrl+clicking o ...

typescriptwebstorm

Issue encountered while using Typescript with mocha: Unable to utilize import statement outside a module

Exploring the world of unit testing with mocha and trying to create a basic test. Project Structure node_modules package.json package-lock.json testA.ts testA.spec.ts tsconfig.json tsconfig.json { "compilerOptions": { "target&qu ...

javascriptnode.jstypescriptunit-testingmocha.js

Tips on using constructor functions and the new keyword in Typescript

This is a demonstration taken from the MDN documentation showcasing the usage of the new keyword function Car(make, model, year) { this.make = make; this.model = model; this.year = year; } const car1 = new Car('Eagle', 'Talon TSi&apos ...

javascripttypescriptnew-operator

Angular 7: Show selected value upon clicking Radio button

I am having an issue with a radio button where I need to display a value when it is clicked. For example, when the "weekly" option is selected, I want it to display "Weekly" in the "Selection" element. I have tried to implement this but it is not working a ...

angulartypescript

Is there a way to have my accordion adjust automatically?

I have developed a dynamic accordion component that populates its values from the parent component. However, I am facing an issue where each accordion does not respond individually to clicks. Whenever I click on any accordion, only the first one expands an ...

angulartwitter-bootstraptypescriptaccordion

Error involving key mismatch between TypeScript inherited interface and literal string type

There are 3 interfaces (A, B, and C) that all extend from a shared interface (Common). Additionally, there is a container type which holds arrays of these 3 interfaces (Container). The goal is to select one of the arrays and extract a common property from ...

typescripttypescript2.1

I am eager to perform DOM manipulation similar to jQuery but within the context of Angular 6

Is there a way to modify the background color of the main div when a button is clicked? <div> <p>I'd like to be able to change the background color of the parent div by clicking a certain button. </p> <button (click)=" ...

angulartypescriptangular6dom-manipulation

Tips on effectively transferring formarray to another component

I'm attempting to pass a formarray to a child component in order to display the values within the formarray there. Here is my current code, but I am struggling to figure out how to show the formarray values in the child component. app.component.html ...

javascriptangulartypescriptangular-reactive-formsformarray

Nextjs REACT integration for self-service registration through OKTA

Attempting to integrate the Okta SSR feature for user sign-up in my app has been challenging as I keep encountering this error message: {"errorCode":"E0000060","errorSummary":"Unsupported operation.","errorLink& ...

reactjstypescriptnext.jsoktaokta-signin-widget

Find any consecutive lowercase or uppercase letter and include one more

I have a task in Javascript that I need help with. The goal is to insert a special character between a lowercase and uppercase letter when they are matched together. For example: myHouse => my_House aRandomString => a_Random_String And so on... T ...

javascriptregextypescript