feat(changelog): add generic changelog source

[bdovaz]

Changes

Create a new generic changelog source to handle cases where data sources such as unity3d return markdown directly in the changelogUrl field.

API example: https://services.api.unity.com/unity/editor/release/v1/releases?stream=LTS

A markdown example: https://storage.googleapis.com/live-platform-resources-prd/templates/assets/6000_3_11f1_500c5f352f/6000_3_11f1_500c5f352f.md

Context

It comes from here and here

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[bdovaz]

I see that the ChangeLogSource class and everything related to it (repositories, tags, etc) are tightly coupled. And the generic approach “doesn't quite fit”:

1. In the constructor, I pass the data source as null because I’m not going to use it and I can’t (the Unity3D data source doesn’t resolve the repository because Unity is closed-source, so there are no tags or anything similar to resolve).
2. Because of the previous point, I haven’t been able to implement getCompareURL.
3. I implement getAPIBaseUrl, but in my case, it’s obviously “not an API base URL.”
4. I return true in hasValidRepository, but in reality, there isn’t a repository at all.

The getChangeLogJSON function (in index.ts) works with sourceUrl, but as I mentioned earlier, Unity is not open source and there is no source URL, nor does the API work that way, so it directly returns the Markdown in changelogUrl. Because of this, I had to make slight modifications to that function.

In the getChangeLogJSON function (from source.ts), I had to modify how it resolves the cache key due to the reasons mentioned above.

Despite all of the above, I've reached the point where the (changelog) link appears, which leads to the Markdown file: bdovaz/renovate_test#26

I haven't been able to get it to render inline because the sectionize function in release-notes.ts doesn't seem to like Unity's Markdown. I guess because it isn't formatted correctly (it only has sections 3 and 4). But that's another issue for the future that could be addressed in a separate PR.

[viceice]

why this is neeed 🤔

[bdovaz]

As I mentioned in my original post:

The getChangeLogJSON function (in index.ts) works with sourceUrl, but as I mentioned earlier, Unity is not open source and there is no source URL, nor does the API work that way, so it directly returns the Markdown in changelogUrl. Because of this, I had to make slight modifications to that function.

In other words, I try to use sourceUrl as usual, and if that fails, I fall back to registryUrl. Unless you can suggest a better option for me to use later in detectPlatform, this is the only solution I could come up with that I know will always be set.

In the case of Unity, in the link to an API call that I included in the PR description, you can see that the Markdown links have nothing to do with Unity. They’re hosted on Google Cloud.

I can't use changelogUrl because it doesn't refer to anything in Unity, and I can't filter by it.

[viceice]

you probably need to rebase onto main or merge main and fix this

[viceice]

store detectPlatform(baseUrl) call into a variable and reuse (perf)

[viceice]

Are you sure changelogUrl is always set here?

[bdovaz]

I don't have much experience with the codebase, but at least I know that in the test I ran mentioned in this comment, it goes through this code and ends up generating the link with the text (changelog).

I know that sourceUrl is empty in the case of the unity3d data source, so if changelogUrl were also empty in the subsequent calls to getCacheKey, the code would throw an error—but it doesn't.