Code coverage

Hi devs, maybe you can bring some light to this.

Is it possible to get code coverage as featured in chrome 59 in an understandable way (reporting lines used, unused, percentage)?

I tried to use the Profiler methods but I get function offsets(lines?) and counts that does not match if I use the coverage feature manually in Chrome.

I have some tests running in localhost:3000. The execution takes 10 seconds (I have a few), so is there a way to extend the recording of the coverage to 10 secs? using setTimeout?.

I’m lost , I’m not grasping this 😦

My code:

const CDP = require('chrome-remote-interface');

CDP((client) => {
  // extract domains
  const {
    Network,
    Page,
    Profiler
  } = client;
  // setup handlers
  Network.requestWillBeSent((params) => {
    console.log(params.request.url);
  });

  // enable events then start!
  Promise.all([
      Network.enable(),
      Page.enable(),
      Profiler.enable(),
      Profiler.startPreciseCoverage()
    ])
    .then(() => {
      return Page.navigate({
        url: 'http://localhost:3000'
      });
    })
    .then(() => Profiler.getBestEffortCoverage())
    .then((data) => data.result.forEach((el) => {
      console.log('-----', el.url)
      el.functions.forEach((el) => {
        console.log('--', el.functionName)
        console.log('ranges', el.ranges)
      })
    }))
    .catch((err) => {
      console.error(err);
      client.close();
    });
}).on('error', (err) => {
  // cannot connect to the remote endpoint
  console.error(err);
});

some output

-- myFunction
ranges [ { startOffset: 907, endOffset: 1490, count: 1 } ] // But it is a 3 line function and it is not executed!! 

All the best.

[sergueyarellano]

For traceability purposes:

https://groups.google.com/forum/#!topic/chrome-debugging-protocol/ILVA8tv7sSc

http://www.mattzeunert.com/2017/03/29/how-does-chrome-code-coverage-work.html

[cyrus-and]

The scriptSource is:

"\n\nfunction foo(x) {\n    return Math.sin(x);\n}\n\nfunction bar() {\n    let x = 0.1;\n    for (i = 0; i \u003C 10000; i++) {\n        x = foo(x);\n    }\n    return x;\n}\n\nsetInterval(bar, 1000);\n\n"

The offsets are relative to this string, so for example:

> foo = scriptSource.slice(2, 45)
'function foo(x) {\n    return Math.sin(x);\n}'
> console.log(foo)
function foo(x) {
    return Math.sin(x);
}

You can roughly get the number of lines of the script (or of any range or function) with:

> scriptSource.split('\n').length
17

For what concerns count I’m a bit puzzled, it seems to be always 1 even though the function foo is called 10000 times per second… The documentation says:

Collected execution count of the source range.

But if you’re just interested in the coverage it doesn’t really matter, I guess. You may want to ask this in the Google Group.

Cheers! 😃