🚀 Feature: Report file name where a test fails

[twitchard]

Is it possible to have mocha report the filename containing a failed test? Could I write a reporter that did this? Or would I have to build support for it, and then write such a reporter? Not at all familiar w/ the mocha codebase yet, but I'd be willing to take a dive in and try out contributing this if the Mocha community would welcome it.

After a test fails, I frequently find myself grepping the title of the test to determine the filename so I can then run the test in isolation.
Reporting the filename would save me a step.

[Bamieh]

which reporter are you using? AFAIK all mocha reporters call the epilogue when the run is done. In which the error stack is displayed

for example, the error above is happening in index.js line 3 column 11

[twitchard]

The error stack is not guaranteed to contain the filename of the failing test. If the test times out, or if it fails due to an asynchronously thrown exception, I often have to go hunting. In my application this ends up being about fifty percent of the time.

[twitchard]

An example:

$ cat test.js
describe('a mocha test that times out', function () {
    it ('does not display the filename containing the failing test', function (callback) {

    })
})
$ $(npm bin)/mocha test.js


  a mocha test that times out
    1) does not display the filename containing the failing test


  0 passing (2s)
  1 failing

  1) a mocha test that times out
       does not display the filename containing the failing test:
     Error: Timeout of 2000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves.

[Bamieh]

Fair enough, this could be added in the epilogue in the base reporter. The epilogue is called by all mocha reporters to show the number of fails / passes, and where the failure happened.

[dfberry]

I would like to fix this bug but have an issue with the suggestion from @Bamieh. The epilogue only has access to the flat stats object.

{
  "suites": 1,
  "tests": 1,
  "passes": 0,
  "pending": 0,
  "failures": 1,
  "start": "2018-01-15T20:29:17.733Z",
  "end": "2018-01-15T20:30:24.430Z",
  "duration": 66697
}

The runnable.js has 2 points where this error might be output (line 239 and line 299). I could just add it to the end of the string at that point.

if (!err && self.duration > ms && self._enableTimeouts) {
      err = new Error('Timeout of ' + ms +
      'ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves. ' + self.file);
    }

The result looks like:

 Error: Timeout of 200ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves. C:\Users\dinab\repos\mocha\mocha-pr-xxx\test\reporters\dina.spec.js

How would adding it to the epilogue stats be helpful? I'm trying to understand as I don't know the interior of the library that well.

[boneskull]

We need to know exactly where this information is supposed to be printed by a reporter, and which reporters print it, or don't.

Let's put the brakes on rushing to change things before we agree what we expect Mocha to do.

[boneskull]

@twitchard

For timeouts:

Can this problem not be solved by making your suites and test names more unique? The spec reporter will print the timeout message directly after the suite and test name. Note that we can't generate a stack trace because the test doesn't actually fail on its own (among other reasons like #3119).

For async exceptions:

When an async exception is thrown, you should get a stack trace. Do you have an example of where this is not happening?