This ticket was split from DRIVERS-1677, please see that ticket for a detailed description.

This ticket is meant to implement changes to Unified spec test runner to support logging in order to
facilitate the rest of the work for NODE-3974.

Unknowns

• What exactly should the failures for the CLAM spec tests look like?
  • See Testing Requirements

Acceptance Criteria

Implementation Requirements

• Implement new operators
  • Implement $$matchAsRoot operator
  • Implement $$matchAsDocument operator

• Implement matching and interpretation of new properties
  • Implement expectLogMessages property
  • Implement expectedLogMessages property
  • Implement expectedLogMessagesForClient property
  • Implement observeLogMessages property
• Stub out mechanism for UnifiedMongoClient to be able to collect logs from MongoLogger

Testing Requirements

• Pull in the CLAM spec tests
• Ensure that CLAM spec tests fail for "right reasons"
  • For tests that check for log messages using the new matching operators/properties, the tests should fail on the absence of the expected log messages and not because the test runner fails to recognize the new operators/properties.
• Add unit tests for $$matchAsRoot and $$matchAsDocument operators