toHaveStyle for property `font-size` behaves incorrectly for number values

• @testing-library/jest-dom version: 6.1.5
• node version: 20.3.1
• jest (or vitest) version: 0.34.1
• npm (or yarn) version: 9.6.7

Relevant code or config:

render(<div data-testid="element" style={{ fontSize: 8 }} />)
expect(screen.getByTestId('element')).toHaveStyle({ fontSize: 1 })

What you did:

I expected the above assertion to fail

What happened:

The test passes instead!✅

Reproduction:

Problem description:

the assertion is clearly incorrect and can easily cause bugs

Suggested solution:

I have not thought of a solution yet but would like to investigate this issue during my off hours.