[SalesForce] Setting Default Value for Lightning Web Component Test

I'm writing unit test for my LWC. For some of the methods and features that I'm testing, it looks at the values of a field and then does something. For example:

let field = this.template.querySelector('.field-class');
if (field.value == 'Matching Value') {
    let secondField = this.template.querySelector('.another-field-class');
    secondField.value = 'Default Value';
}

So when I'm writing the test I'll have something like this:

describe('test-element', () => {
    var element;

    beforeEach(() => {
        element = createElement('c-test-element', {
            is: TestElement
        });

        document.body.appendChild(element);
    });

    afterEach(() => {
        while (document.body.firstChild) {
            document.body.removeChild(document.body.firstChild);
        }
    });

    it('should set the default value'), () => {
        let field = element.shadowRoot.querySelector('.field-class');
        field.value = 'Matching Value';

        const form = element.shadowRoot.querySelector('lightning-record-edit-form');
        form.dispatchEvent(new CustomEvent('load'));

        let secondField = element.shadowRoot.querySelector('.another-field-class');
        expect(secondField.value).toBe('Default Value');
    });
});

It works fine, but the problem is that when I run the test I get a warning message like this:

console.warn
node_modules/@lwc/engine/dist/commonjs/es2017/engine.js:208
[LWC warning]: If property value decorated with @api in [object:vm undefined (213)] is used in the template, the value
Matching Value set manually may be overridden by the template,
consider binding the property only in the template.

I've found a way to avoid this by adding getters and setters to the the actual component and using those, but that doesn't seem like the best solution since I only need them for tests. Especially since to get full code coverage I have to write specific test for them.

Is there a way to set the value of a field for a test without getting the warning message?

I apologize for any typos in the code, I freehand wrote it.