Tests for twisted.conch.checkers.
| Class | HelperTests | Tests for helper functions verifyCryptedPassword,_pwdGetByNameand_shadowGetByName. | 
| Class | SSHPublicKeyDatabaseTests | Tests for SSHPublicKeyDatabase. | 
| Class | SSHProtocolCheckerTests | Tests for SSHProtocolChecker. | 
| Class | UNIXPasswordDatabaseTests | Tests for UNIXPasswordDatabase. | 
| Class | AuthorizedKeyFileReaderTests | Tests for checkers.readAuthorizedKeyFile | 
| Class | InMemorySSHKeyDBTests | Tests for checkers.InMemorySSHKeyDB | 
| Class | UNIXAuthorizedKeysFilesTests | Tests for checkers.UNIXAuthorizedKeysFiles. | 
| Class | SSHPublicKeyCheckerTests | Tests for checkers.SSHPublicKeyChecker. | 
| Class | _DummyException | Fake exception to be used for testing. |