Adding and ensuring more dedicated tests

[tinect]

Feature Request

Using different adapters, I always see different behaviours. This could be avoided, if there were more dedicated tests in AdapterTestUtilities.

• fileExists should not be true, if it is a directory (chore: add tests to test fileExists onto directory and vice-versa #1789)
• directoryExists should not be true, if it is a file (chore: add tests to test fileExists onto directory and vice-versa #1789)

Currently, It is not clear what should happen, when:

• move/copy any file onto any other existing file?
  • a few throw exceptions, some just overwrite
• move/copy any file to the same destination?
  • a few throw exceptions, others remove the file, others just updating the visibility
• deleteDirectory which does not exist
  • a few throw exceptions, others ignore it

[tinect]

@frankdejonge is this something we can talk about for v4?