Native types exceptions can crash Mocha runner

[fargies]

Prerequisites

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Description

Native types exceptions in async callbacks raises an exception in Mocha runner, stopping the test-sequence.

Steps to Reproduce

throw a native type exception in an async test.
See associated merge request.

Expected behavior: exception should be caught and test should fail

Actual behavior: runner stops with following stack trace:

.../mocha/lib/runner.js:707
  err.uncaught = true;
               ^
TypeError: Cannot create property 'uncaught' on string 'error'
    at Runner.uncaught (.../mocha/lib/runner.js:707:16)
    at process.uncaught (.../mocha/lib/runner.js:820:10)
...

Reproduces how often: 100%

Versions

• The output of mocha --version and node node_modules/.bin/mocha --version: 5.0.5
• The output of node --version: v8.6.0
• The version and architecture of your operating system: macOs 10.13.3
• Your shell (bash, zsh, PowerShell, cmd, etc.): zsh
• Your browser and version (if running browser tests):
• Any other third party Mocha related modules (with versions):
• The code transpiler being used:

Additional Information

Not really sure that the proposed fix will work in all environments, there may be better ways to fix this.

[boneskull]

Throwing a string is not supported. If there's some other use case, please explain.

[fargies]

When the code under test throws something that is not an Error in a synchronous test it seems to be properly handled and converted to an Error, displaying a messages like (using a string is really only an example):
Uncaught Error: the string "error" was thrown, throw an Error :)

When the same piece of code is ran in an asynchronous callback the runner crashes.

The idea was to have the same behavior in synchronous and asynchronous code, but you're right the first merge request was not properly fixing the issue.

[stale]

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[suppagoddo]

Any updates on this?