console.warn statements that occur during tests should be encapsulated and tested

The `console.warn` statements that occur (and are expected to occur) during testing should be wrapped in another function, and this function should be used to check whether a specific statement occurred or not. The default should be that _no_ `console.warn` statements should be printed.

Start by locating the console.warn statements and the tests that trigger them. Encapsulate expected warnings behind a test helper and verify that expected warnings are checked while no unexpected console.warn output is printed.

Written by the indexing model from the issue text.