The test suite currently passes even if it cannot connect to a local MongoDB instance. This is intentional so that the test suite passes even if no MongoDB instance is running.

However, on Evergreen we know that the test suite should connect and run the entire test suite. We should add some logic to make the test suite fail if the tests are skipped. The test suite should fail with an error if it cannot connect and an environment variable, eg "SHOULD_CONNECT", is set.

This would prevent PYTHON-1414 from happening again.