+ | TestOutputFileMD5 of seq * string
+
+ (* Run the command sequence and expect the output of the final
+ * command to be a string which is a block device name (we don't
+ * check the 5th character of the string, so "/dev/sda" == "/dev/vda").
+ *)
+ | TestOutputDevice of seq * string
+
+ (* Run the command sequence and expect the final command (only)
+ * to fail.
+ *)