Testing local generators which only update existing files

[mrvonwyl]

Hi everybody.

I am new to NX plugins and especially local generators and started writing my own.
My current use case is to add a Docker Build target to the project.json of an existing app. But there are many more.

I update the project.json like this:

const projectConfiguration = readProjectConfiguration(tree, options.project);

updateProjectConfiguration(tree, options.project, {
  // contents
});

The generator works as expected. However, I also want to test the generator and the documentation seems to be thin.
What I found so far is that a temporary Tree can be created with createTreeWithEmptyWorkspace().
But how would I go forward from here? Do I need to use tree.write() for every required file?
And how can I satisfy the existence of a project, since I rely on the project name to locate the project.json?

Thank you for any hint on this!

[mrvonwyl]

After scouring the NX generators source code, I stumbled upon addProjectConfiguration.
And searching for it, I found https://nx.dev/nx-api/devkit/documents/nx_devkit.

I hope this helps anyone else looking for testing their generators.

Feel free to add to the discussion.