Mockgo
mockgo is a Node.js library which simplifies the task to create integration tests using a real MongoDB server.
When integrating mockgo with your tests, it will take care of downloading the right mongo binaries, initialize a real in-memory mongo database and clean it at the end of the test.
Contribution
I was using mockgo in various Node.js projects for writing integration tests that used a real mongo database but still run fast and in memory.
However some of its dependencies were outdated, which was limiting the MongoDB versions that could be used in our tests.
I submitted a PR that ended up refactoring mockgo not just to update its dependencies, but also to use promises and ended up released as the v2 of the library.