Create a JS utility to generate a GitHub comparison URL

If you haven’t already, check out our contributing guidelines for onboarding!

---

Problem

As part of our new Expensify.cash Deploy & QA process, we’ll need an easy way to view differences between versions. To do so, we’ll generate links to a GitHub comparison.

Why is this important?

This will be an important step for engineers to be able to view changes introduced by a release and track regressions.

Solution

Create a Javascript utility function in expensify-common called generateVersionComparisonURL that takes in:

1. A repoSlug
2. A tag (version number)
3. A semverLevel that’s one of `[‘MAJOR’, ‘MINOR’, ‘PATCH’, ‘BUILD’]

And then:

1. Fetch the tags of the repo
2. Search through the results to find the tag of the previous version of the appropriate semverLevel.
3. Return a URL formatted like: https://github.com/Expensify/Expensify.cash/compare/<previous_version_tag>...<current_version_tag>

Note: If it doesn’t already exist, this function should be stored in a class called GithubUtils that takes in an authenticated octokit client as a parameter to its constructor. This function will be used from the context of Github Actions, where we’ll always have an authenticated client available.

To be considered complete

• Document testing
• Provide automated unit tests.

Internal issue Upwork listing

[roryabraham]

Whatever the case, a very comprehensive set of automated tests will be the key to success here 👍

[roryabraham]

@SombreroElGringo Your proposal here looks good. Just a few comments:

For select the good tag we should slip or use a regex to get the good semverLevel values from the tags received from the API.

You should use the semver library to accomplish this instead of writing your own regexes.

Also, your examples aren’t exactly correct. It should provide a comparison between the highest version of the previous level. Let’s say we have the following tags: 2.2.2-1, 2.2.2, 2.2.1, 2.2.0, 2.1.0-2, 2.1.0-1, 2.1.0, 2.1.2, 2.0.0, 1.1.0 and 1.0.0

generateVersionComparisonURL(“my-repo”, “2.2.2”, “MAJOR”) should return https://github.com/Expensify/Expensify.cash/compare/1.1.0...2.2.2 not 1.0.0...2.2.2

generateVersionComparisonURL(“my-repo”, “2.2.2”, “MINOR”) should return https://github.com/Expensify/Expensify.cash/compare/2.1.2...2.2.2 not 2.1.0

generateVersionComparisonURL(“my-repo”, “2.2.2”, “PATCH”) should return https://github.com/Expensify/Expensify.cash/compare/2.2.1...2.2.2

generateVersionComparisonURL(“my-repo”, “2.2.2-1”, “BUILD”) should return https://github.com/Expensify/Expensify.cash/compare/2.2.2...2.2.2-1 not 2.1.0-2...2.2.2-1

It’s a bit hard to describe with words, but it should provide a comparison between the version passed as a parameter, and the highest version of the previous SEMVER_LEVEL version.

In the case of BUILD, it will always be a comparison with the previous PATCH version. Does that make sense?