Collect coverage report data

[nib-bturner]

It would be awesome to see this tool collect test coverage summaries.

Not only can I see it being really useful to see the latest test coverage, but also how coverage evolves during the lifecycle of a development project.

[pda]

This repository has moved into the buildkite/bktest monorepo — this project now lives at test-collector-javascript/, with full git history carried over.

As part of the move we're closing open issues here. If this still needs attention, please open a new issue in buildkite/bktest and link back to this one.