Miscellaneous improvements in unit tests.

End statements with semicolons, to be consistent with the surrounding
code.

Added a new unit test to ensure environment variables are honored when parsing a
connection string.

Added a TODO to cleanup a test that emits messages using console.log().

Correct a query's syntax. Looks like a good thing to do even though the syntax
doesn't matter in mocked out tests.

Removed a test that tests for SELECT tags; AFAIK, SELECT commands don't emit a
tag.