sindresorhus/aggregate-error

Make it more spec compliant

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#4 opened on Jan 10, 2018

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 (15 comments) (0 reactions) (0 assignees)JavaScript (247 stars) (18 forks)user submission
enhancementhelp wanted

Description

When used with mocha the errors are displayed twice. Is there a way to have it only display once?

const AggregateError = require('aggregate-error')

it('should fail', function() {
  throw new AggregateError([
    new Error('first'),
    new Error('second')
  ])
})

The report is

  1) should fail

  0 passing (12ms)
  1 failing

  1) should fail:
     
    Error: first
        at Context.<anonymous> (/Users/williamrusnack/Documents/event_sequencing/try_aggregate-error.js:5:5)
        at callFn (/Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runnable.js:354:21)
        at Test.Runnable.run (/Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runnable.js:346:7)
        at Runner.runTest (/Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runner.js:442:10)
        at /Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runner.js:560:12
        at next (/Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runner.js:356:14)
        at /Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runner.js:366:7
        at next (/Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runner.js:290:14)
        at Immediate.<anonymous> (/Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runner.js:334:5)
    Error: second
        at Context.<anonymous> (/Users/williamrusnack/Documents/event_sequencing/try_aggregate-error.js:6:5)
        at callFn (/Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runnable.js:354:21)
        at Test.Runnable.run (/Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runnable.js:346:7)
        at Runner.runTest (/Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runner.js:442:10)
        at /Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runner.js:560:12
        at next (/Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runner.js:356:14)
        at /Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runner.js:366:7
        at next (/Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runner.js:290:14)
        at Immediate.<anonymous> (/Users/williamrusnack/Documents/event_sequencing/node_modules/mocha/lib/runner.js:334:5)
  AggregateError: 
      Error: first
          at Context.<anonymous> (try_aggregate-error.js:5:5)
      Error: second
          at Context.<anonymous> (try_aggregate-error.js:6:5)
      at Context.<anonymous> (try_aggregate-error.js:4:9)

Contributor guide

Tech stack
javascriptnodejs
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic JavaScriptFamiliarity with MochaUnderstanding of AggregateError
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
The issue reports that errors are printed twice when using AggregateError in Mocha. The fix likely involves modifying the AggregateError constructor or its toString/inspect method to avoid duplicate output. Start by examining the current source code of aggregate error, particularly the error creation and how Node.js displays errors. Also check the ECMAScript spec for AggregateError to understand expected behavior. Look at Mocha's error handling to see if it already handles AggregateError specially. The 15 comments may contain proposed solutions; examine them for clues.