title: What's the difference between '.toMatchObject' and 'objectContaining'
body: <p>I have written the following test:</p>
  
  <pre><code>it('Can decrement the current step', function () {
      expect(reducer(TestState, { type: 'GOTO_PREVIOUS_STEP' })).toMatchObject({ currentStep: 4 });
  });
  
  it('Can decrement the current step v2', function () {
      expect(reducer(TestState, { type: 'GOTO_PREVIOUS_STEP' })).toEqual(expect.objectContaining({ currentStep: 4 }));
  });
  </code></pre>
  
  <p>both of them seem to pass the test, is there any difference between them? is there a performance impact between them? </p>