Updating by id so don't need to specify the multiple option as false.
Change tests db name to fit class
Echo out cover success/fail.
Take out extra space in coverage check.
Don't use original keys with iterator_to_array in tests.

The mongo cursor gives back the _id as the key when looping over it (which iterator_to_array does), so we were one of in the expected array.
Should allow empty collection in tests in case the readers start before writers.

This drove me crrraaaazy for a long while !