As it has been described in the section Penneo frontend codebase originally had been created as a multi repository project

As it has been described in the section Penneo frontend codebase originally had been created as a multi repository project, consisting of separate and independently versioned packages which were the following: `fe-auth`, `fe-branding`, `fe-casefiles`, `fe-forms`, `fe-translations`.
All of these packages were highly dependent on the `fe-application-loader` project which served as a loader package for them. All Penneo frontend packages were linked with the master project with npm link. The application loader project used to import also other dependencies among the others React packages: `react` and `react-dom`. The other Penneo packages did not have to install these dependencies even though they required them. The application loader used to create a code bundle using Gulp and Browserify. After creating the bundle all the packages together with the loader package would become as one so the React dependencies could be accessed by all the packages without explicitly including them in their own `node_modules` directory.

Usually splitting up large projects into smaller independent packages is a good idea. However in this case it was particularly bad solution due to the fact that all the separate packages were highly coupled so there was no actual reason for keeping them apart.
Furthermore the multi repository structure made the project very complicated to test.
When attempted to test `fe-casefiles` package, the Jest framework threw an error saying it could not find React dependencies because obviously that package did not have them installed. It could not have them because if it did, after creating a bundle an error would be thrown due to having two copies of React loaded. The difficulty level for creating simple tests have escalated very quickly as more errors appeared while trying to fix it.

A decision about changing a strategy has been made. Following some of the biggest projects out there like Babel, React, Angular or Jest a new idea came up. It was to organize all the packages into one multi-package repository. Lerna is a tool that helps to optimize a workflow for coping with this kind of projects.
Giving a shot to Lerna a new file structure has been created. Following the instructions from Lerna’s GitHub repository page all Penneo frontend packages have been moved into one common package, a new package.json file for this directory has been created and the whole directory has been turned into Lerna repo by creating lerna.json configuration file.