Tests broken and false positive

[jehy]

Unit tests on project only pass if you use yarn with yarn.lock.

If you try rm ./node_modules -rf && npm i && npm test - then tests fail.

On production, yarn.lock in package is not used even by yarn itself - it only uses top level lock file - and it means that those test cases will fail on production code.

We can either use shrinkwrap-json to ensure that project's transitive dependencies with be installed with versions we want - or remove confusing yarn lock and fix project to work fine with current deps.

[ljharb]

I'd prefer to remove all lockfiles, and use npm instead of yarn, to mirror the majority usage of our users.