Replace tests

Describes the tests needed to validate the Replace functionality.

Basic replace

1.  Attempt to replace a file. The file should exist in the collection, providing the correct checksum the new file.
   1. The new file should now be the one in the collection. Use the getChecksum client to verify this.

Bad old file checksum

1. Attempt to replace a file, providing the wrong checksum for the old file.
   1. The file shouldn't be replaced, and the user should be informed that the operation failed due to the invalid checksum.

Bad new file checksum

Attempt to replace a file, providing a bad checksum for the new file.

Missing file replace

Attempt to replace a file that does not exist in the collection

Unreachable file replace

Attempt to replace a file in the collection, providing the correct checksums, but a wrong url (the url validates, but no file is found)