Add file system interface tests
Code comment explaining the scope:
* Test the derived FileSystem interface classes which call the file system specific * executables via the SupportedFileSystems class. Rather than mocking command execution * and returned output just run real commands, effectively making this integration testing. * * Test case setup determines the file system supported actions using * get_filesystem_support() and individual tests are skipped if a feature is not * supported, just as GParted does for it's actions. * * Each test creates it's own sparse image file and a fresh file system, performs a test * on one FileSystem interface call and deletes the image file. This makes each test * independent and allows them to run as a non-root user, provided the file system command * itself doesn't require root. Errors reported for a failed interface call will include * the GParted OperationDetails, which in turn includes the file system specific command * used and stdout and stderr from it's execution.
(Some of the progress can be seen in the fs-test-* branches in my