Add Custom Filename support for coveralls.json

[jowi-dev]

Problem

When running an umbrella app's coveralls in partitioned instances - a way to specify reports is needed for tools like CodeCov to merge reports - this is helpful when running GH actions as a matrix for each app, or even if running the same app in partitions.

Proposal

Leverage the same export flag that exists for .coverdata files and allow the name to be used instead of the hardcoded excoveralls.json if it exists. That way predictable filenames can be given and default behaviour preserved.

[jowi-dev]

@parroty - Any thoughts on this one?

[parroty]

Thanks for the update 🙇 . Could you help me to add some usage examples for understanding the behavior well? (maybe in the README?). I am assuming the default behavior doesn't change and adding this new option might not break existing usage.

[jowi-dev]

Hey! So the default behavior is not changed at all, really I wanted a mechanism to piggyback on the existing

test_coverage: [tool: ExCoveralls, export: "myReport"]

Currently in a coveralls.json export, the file would be named excoveralls.json on export no matter what. Once these changes are merged, the file will be exported as myReport.json

I'll add a little spot in the readme for it

[jowi-dev]

@parroty README updated

[parroty]

Thank you (and sorry being late to respond), please allow some time to publish.