Which function do you want to add comments to?

TestGetMountRoot in pkg\ddc\alluxio\utils_test.go.

What comments do you want to add?

// TestGetMountRoot tests the function that retrieves the mount root directory.
// It checks if the function correctly returns the expected mount root path based on the environment variable MOUNT_ROOT.
// The test sets the MOUNT_ROOT environment variable to a specific path and verifies that the function returns the correct mount root path.revise twice.
// The expected mount root path is constructed by appending "/alluxio" to the value of MOUNT_ROOT.