TypeScript class with private fields throwing unexpected errors in Jest tests
I'm confused about I'm relatively new to this, so bear with me. I have a TypeScript class that defines several private fields and methods. When I try to test this class using Jest, I'm working with a `TypeError: want to read property '...' of undefined` behavior, which seems to stem from trying to access a private method. Here's a simplified version of my class: ```typescript class MyClass { private value: number; constructor(initialValue: number) { this.value = initialValue; } private calculateSquare() { return this.value * this.value; } public getSquare() { return this.calculateSquare(); } } ``` In my Jest test, I have: ```typescript import MyClass from './MyClass'; describe('MyClass tests', () => { let myClass: MyClass; beforeEach(() => { myClass = new MyClass(5); }); test('should return the square of the value', () => { expect(myClass.getSquare()).toBe(25); }); test('should call private method calculateSquare', () => { // This line is causing the TypeError myClass.calculateSquare(); }); }); ``` I understand that private methods should not be accessible outside the class, but I'm trying to ensure that the private method is called properly within my tests. I've tried using `jest.spyOn` to mock private methods, but that doesn't work since they are not accessible. I also considered refactoring my class to include a wrapper method, but I'm not sure if that's the best approach. Has anyone experienced similar issues with private methods in Jest? What’s the best practice for testing such cases without exposing private methods unnecessarily? Any ideas what could be causing this? I'm working on a CLI tool that needs to handle this. I'd really appreciate any guidance on this. I'm coming from a different tech stack and learning Typescript. Thanks for your help in advance!