// workaround from https://github.com/ryanclark/karma-webpack/issues/498#issuecomment-790040818 const output = { path: require("os").tmpdir() + '/' + '_karma_webpack_' + Math.floor(Math.random() * 1000000), } config.set( { webpack: {... createWebpackConfig(), output}, files: config.files.concat([{ pattern: `${output.path}/**/*`, watched: false, included: false, }] ) } )