JEST with Handlebars configuration

Question

I am trying to add Jest to existing project and i have problem with configuration.

1. To solve problem with modules and es6 i added rollup-jest package (we are using rollup on our project)
2. To solve problem with handlebars i tried to use jest-handlebars package but i got problem

      Code transformer's `process` method must return an object containing `code` key

      with processed string. If `processAsync` method is implemented it must return

      a Promise resolving to an object containing `code` key with processed string.

      Code Transformation Documentation:

      https://jestjs.io/docs/code-transformation```
 Has anybody aby similar problem with jest plus handlebars configuration or can anybody help me with code transformator?

EDIT:
i added preprocessor.js file with: 

module.exports = {
  process(src) {
    const code = `
    const Handlebars = require('handlebars');
    module.exports = Handlebars.compile(\`${src}\`);
    `
    return {
        code: code
    };
},

};

and change my packaged.json to:
```  "jest": {
    "preset": "rollup-jest",
    "collectCoverage": true,
    "modulePaths": [
      "./",
      "./node_modules"
    ],
    "moduleFileExtensions": [
      "js",
      "hbs",
      "ts"
    ],
  
    "transform": {
      "\\.js$": "rollup-jest",
      "^.+\\.hbs$": "<rootDir>/jestHbsTransformer.js",
      "^.+\\.ts?$": "ts-jest"
    }
  }
}```
and it is still not working ;)
enter code here