Prerequisites

• [x ] Checked that your issue hasn't already been filed by cross-referencing issues with the faq label
• [x ] Checked next-gen ES issues and syntax problems by using the same environment and/or transpiler configuration without Mocha to ensure it isn't just a feature that actually isn't supported in the environment in question or a bug in your code.
• [x ] 'Smoke tested' the code to be tested by running it outside the real test suite to get a better sense of whether the problem is in the code under test, your usage of Mocha, or Mocha itself
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Description

Issue #3243 shipped with v6.0.0 throw a deprecation warning or an error if --throw-deprecation is enabled with all CoffeeScript tests since the language support implicit returns.

Steps to Reproduce

The following minimalist test case:

describe 'My Suite', () ->
  it 'run a test', () ->
    console.log 'yes'

Throw the error "DeprecationWarning: Suites ignore return values. Suite "My Suite" in /package/test/my/test.coffee returned a value; this may be a bug in your test code"

A temporary workaround include returning undefined:

describe 'system.authconfig', () ->
  it 'fuck around', () ->
    console.log 'yes'
  undefined

Versions

• The output of npx mocha --version : 6.0.0
• The code transpiler being used: CoffeeScript
• Other information not relevant

Additional Information

I understand the motivation behind #3243. One way to please everyone is to detect if the return value found in the suite is not the same as the one returned by it.