webpack/test/configCases/source-map/default-filename-extensions-js/index.js

it("creates source maps for .js output files by default", function() {
  var fs = require("fs");
  var source = fs.readFileSync(__filename, "utf-8");
  var match = /sourceMappingURL\s*=\s*(.*)/.exec(source);
  expect(match[1]).toBe("bundle0.js.map");
});