sourcemap is not generated

[simon998yang]

i saw in webpack.config.js

if (isTest) {
config.devtool = 'inline-source-map';
}
else if (isProd) {
config.devtool = 'source-map';
}
else {
config.devtool = 'eval-source-map';
}

But when i run 'npm run build' , I cannot find sourcemap is generated.