2 Electron Windows open if setting the "--show" flag?

[conanak99]

When I tried to set the --show flag in karma.conf.js, the launcher open 2 electron windows instead of 1. (1 with Karma and 1 empty)

This is my karma.conf.js

    preprocessors: {
      '**/*.js': ['electron'],
      '**/*.spec.js': ['electron']
    },
    client: {
      useIframe: false
    },
    browsers: ['CustomElectron'],
    customLaunchers: {
      CustomElectron: {
        base: 'Electron',
        flags: ['--show']
      }
    }

If I remove the --show flag, the unit test is run headerless as expected.

[twolfson]

Sorry for the slow reply. This is the expected behavior; Karma operates on 2 contexts:

• A parent context which tracks how tests are runnning and reports those back to Node.js
• A child context which runs the actual tests (e.g. sets up Mocha hooks, loads Mocha test suite)

Normally Karma loads the child context in an iframe of the parent context. However, we use client.useIframe which causes Karma to load the child context as a separate window. This is required due to security issues for iframes in Electron