TS2339: Property 'value' does not exist on type 'Component<{}, {}, any>'. react renderer unit test

TS2339: Property 'value' does not exist on type 'Component<{}, {}, any>'. react renderer unit test#

 
    import React from 'react';
    import { render, screen } from '@testing-library/react';
    
    const MyComponent = () => {
        const [value, setValue] = React.useState('');
        
        const handleChange = (event: React.ChangeEvent<HTMLInputElement>) => {
            setValue(event.target.value);
        }
        
        return (
            <div>
                <input type="text" value={value} onChange={handleChange} />
            </div>
        );
    };
    
    describe('MyComponent', () => {
        it('renders correctly', () => {
            render(<MyComponent />);
            
            const inputElement = screen.getByLabelText('text-input');
            expect(inputElement.value).toBe(''); // error TS2339: Property 'value' does not exist on type 'Component<{}, {}, any>'
        });
    });

This error occurs when you try to access a property that does not exist on a React component type. In this case, we are trying to access the value property of an input element in a unit test using the screen.getByLabelText() method provided by the @testing-library/react package. However, the TypeScript compiler is throwing an error because it does not recognize the value property as part of the Component<{}, {}, any> type.

To fix this error, we need to provide a type annotation for the inputElement variable so that TypeScript knows it is an HTMLInputElement. We can do this by using the as keyword and providing the type annotation in angle brackets:

 
    const inputElement = screen.getByLabelText('text-input') as HTMLInputElement;
    expect(inputElement.value).toBe('');

This will tell TypeScript that inputElement is an HTMLInputElement and that it has a value property.

Alternatively, we can use the querySelector() method to select the input element and avoid the type annotation altogether:

 
    const inputElement = document.querySelector('input[type="text"]') as HTMLInputElement;
    expect(inputElement.value).toBe('');

This will also work because the querySelector() method returns an Element object, which we can cast to an HTMLInputElement using the as keyword.