Avoid whitespace changes for arrays in automatic config migrations

[JuJup]

What would you like help with?

I would like help with my configuration

How are you running Renovate?

Self-hosted

If you're self-hosting Renovate, tell us which platform (GitHub, GitLab, etc) and which version of Renovate.

GitLab

Please tell us more about your question or problem

I recently got a config migration PR from Renovate, which was correctly migrating some fields. However, it added whitespaces to all of my arrays.

Example:

Before:
{
     "matchFileNames": ["some-dir/**"],
     "matchDatasources": ["maven"],
     "matchDepTypes": ["dependencies"],
     "excludePackagePrefixes": [ "some-package:"],
},

After:
{
     "matchFileNames": [
       "some-dir/**"
     ],
     "matchDatasources": [
       "maven"
     ],
     "matchDepTypes": [
       "dependencies"
     ],
     "matchPackageNames": [
       "!some-package:{/,}**"
     ]
},

As seen in this example, excludePackagePrefixes was successfully migrated, but it also introduced a lot of unnecessary changes. While I prefer the inline arrays if it's a single entry it makes it also harder in the PR to see what really has changed.

I found this Issue where @rarkins explained the same problem. There seems to be a solution with prettier but I can't really get my head around that. When I run the validator locally, it doesn't shatter the JSON and when I run format on the file in VS Code it also doesn't change something.
I don't have an explicit .prettierrc, but even with adding this I couldn't find a solution to my problem.

Can someone point me in the right direction?

Logs (if relevant)

No response

[HonkingGoose]

We want to make "getting config migration PRs from Renovate" the default behavior in a new major version (see #16359). But before we can make it the default, we need to stop/reduce the amount of whitespace changes.

I think this issue is most relevant here, as that is about using a different JSON parser, which may do better with whitespace changes?

• Replace JSON config migration code with jsonc-parser #27972

[JuJup]

Ok so I'll wait for that ticket and the next major version :)
Thank you