old_contents: module.exports = function (config) {
    config.set({
      frameworks: ['mocha'],
  
      files: [
        './node_modules/unexpected/unexpected.js',
        './node_modules/sinon/pkg/sinon.js',
        './lib/unexpected-sinon.js',
        './test/common/browser.js',
        './test/monkeyPatchSinonStackFrames.js',
        './test/unexpected-sinon.spec.js',
      ],
  
      client: {
        mocha: {
          reporter: 'html',
          timeout: 60000,
        },
      },
  
      browserStack: {
        // Attempt to fix timeouts on CI:
        // https://github.com/karma-runner/karma-browserstack-launcher/pull/168#issuecomment-582373514
        timeout: 1800,
      },
  
      browsers: ['ChromeHeadless', 'ie11'],
  
      customLaunchers: {
        ie11: {
          base: 'BrowserStack',
          browser: 'IE',
          browser_version: '11',
          os: 'Windows',
          os_version: '7',
        },
      },
  
      reporters: ['dots', 'BrowserStack'],
    });
  };
  
new_contents: module.exports = function (config) {
    config.set({
      frameworks: ['mocha'],
  
      files: [
        './node_modules/unexpected/unexpected.js',
        './node_modules/sinon9/pkg/sinon.js',
        './lib/unexpected-sinon.js',
        './test/common/browser.js',
        './test/monkeyPatchSinon9StackFrames.js',
        './test/unexpected-sinon.spec.js',
      ],
  
      client: {
        mocha: {
          reporter: 'html',
          timeout: 60000,
        },
      },
  
      browserStack: {
        // Attempt to fix timeouts on CI:
        // https://github.com/karma-runner/karma-browserstack-launcher/pull/168#issuecomment-582373514
        timeout: 1800,
      },
  
      browsers: ['ChromeHeadless', 'ie11'],
  
      customLaunchers: {
        ie11: {
          base: 'BrowserStack',
          browser: 'IE',
          browser_version: '11',
          os: 'Windows',
          os_version: '7',
        },
      },
  
      reporters: ['dots', 'BrowserStack'],
    });
  };
  
subject: Fix karma config