DeprecationWarning in Node 7 when using browserConsoleLogOptions.path.

[chrahunt]

Expected behaviour

Executing test with config that includes browserConsoleLogOptions with path will successully (and quietly) write browser console to the given path.

Actual behaviour

Each time browser console is written to path, a DeprecationWarning appears:

(node:3804) [DEP0013] DeprecationWarning: Calling an asynchronous function without callback is deprecated.

Running using node --trace-warnings node_modules/.bin/karma gives:

(node:12822) DeprecationWarning: Calling an asynchronous function without callback is deprecated.
    at maybeCallback (fs.js:98:42)
    at Object.fs.write (fs.js:729:14)
    at Server.<anonymous> (.../node_modules/karma/lib/server.js:231:10)
    at emitThree (events.js:121:20)
    at Server.emit (events.js:197:7)
    at Browser.onInfo (.../node_modules/karma/lib/browser.js:112:15)
    at Socket.<anonymous> (.../node_modules/karma/lib/events.js:13:22)
    at emitOne (events.js:96:13)
    at Socket.emit (events.js:191:7)
    at .../node_modules/socket.io/lib/socket.js:503:12
    at _combinedTickCallback (internal/process/next_tick.js:73:7)
    at process._tickCallback (internal/process/next_tick.js:104:9)

The relevant line here is Server.<anonymous> (.../node_modules/karma/lib/server.js:231:10). The code in question.

Environment Details

• Karma version (output of karma --version): Karma version: 1.7.0
• Relevant part of your karma.config.js file:

browserConsoleLogOptions: {
  level: 'debug',
  path: 'karma-out.log',
  terminal: false
}

This is with node v7.10.0.

Steps to reproduce the behaviour

git clone [email protected]:chrahunt/TagProReplays.git \
&& git checkout 5da3cb5                             \
&& npm test

Based on the docs we should be waiting for the callback between writes or using fs.createWriteStream.

[chrahunt]

Blocked on #2765 since those are the relevant tests for the changes needed here.

[chrahunt]

Fixed by #2939.