Drop the MongoDB Simpletest collections from a Drupal 7 database

simpletest-clean.js

var collections = db.getCollectionNames();
collections.forEach(function(e) { 
  if (e.match(/^simpletest/)) { 
    db[e].drop();
  }
});

// And the one-liner version, simple to paste.
db.getCollectionNames().forEach(function(e) { if (e.match(/^simpletest/)) { db[e].drop();}});