Correct typo; setup unit test

I would have caught this if I had a test case for HTML Document.
Remove vestigial/incorrect methods

I had long ago overrode these message to prevent the class from being
able to write files but this is not needed nor is it technically valid
since the declarations don't match the parent methods.
Simplify test file name generation

This allows me to rename the files without having to make code changes.
Correct expected value

I made a change earlier to how the application URI should be generated
and neglected to run all tests before committing that change.