Hi, I would like to suggest a feature, can this library capture the timings too?

The onRender callback contains a number of interesting metrics; mainly phase, baseDuration, and actualDuration. It would be great if this profiler wrapper could capture these values. Here's an example of what I would like:

const ExampleComponent = () => <div />;
const TestComponent = withProfiler(ExampleComponent);

it("should capture all renders", () => {
  const { rerender } = render(<TestComponent />);
  rerender(<TestComponent />);

  // `renders` is an array of the captured "phase" parameter
  expect(TestComponent.profiler.renders).toMatchInlineSnapshot(`
    Array [
      "mount",
      "update",
    ]
  `);

  // `timings` is an array of ALL the parameters: 
  console.log(TestComponent.profiler.timings);
  // Logs:
  // Array [
  //   {
  //     phase: "mount",
  //     actualDuration: 2.112893512389,
  //     baseDuration: 2.91723497584,
  //     startTime: 1147.7671834767779,
  //     commitTime: 1157.7768147817643,
  //   },
  //   { phase: "update", ... }
  // ]

  TestComponent.profiler.clear();
});

I have 2 use-cases:

1. Better assertions. In the example above, I'm not limited to just using .toHaveCommittedTimes(#). By exposing the number of renders via Wrapper.profiler.renders, I'm able to make any assertions I want, including snapshots or range testing.

2. Quick access to rendering times. The Wrapper.profiler.timings array would contain the detailed timings for each render. I don't intend to use these values to make assertions (because this kind of perf testing is too unstable), but I do think it could be useful for logging the timings for testing purposes. It would be great to know whether mount or update is taking the most time, and it would be a nice developer tool for attempting to improve performance.

What do you think? (Fwiw, I've got a forked copy that has these implemented, if you'd like to see it)

Since there's "jest": "^21", in deps, looks like the profiler pulls Jest 21 into a project.

Do you think it would be possible to drop this requirement? Let's do peer deps for supported Jest range instead?

Hello @bvaughn

Just stumbled upon this Profiler impl. for Jest. Super excited about all your recent work for React Profiler 👍

In my case, I ran into the following error:

Profiler onRender was never called.
   
This may indicate that you are using a version of React that does not support profiling.

My test in Jest looks like the following:

it('Message', () => {
    const MessageWithProfiler = withProfiler(Message);
 
    renderer.create(
      renderToString(<MessageWithProfiler />),
    );
 
    expect(MessageWithProfiler).toMatchNumCommits();
  });

Is it because you are using a different renderer?

My versions:

React: 16.8.6
Jest: 22.2.2

which should be okay regarding the peer dependencies used by jest-react-profiler.

Any hints on why this may fail? Thanks for your time!