This document defines the coverage for the pthread_mutex_lock function:

Assertion	Tested?
1		YES
2		YES
3		NO  * Error codes are either implementation dependent or 
		      related to the low-priority mutex attributes
		    * When it specifies 'may' fail and not 'shall' fail,
		      it will always return PASS, but will return a 
		      PASS and print out a warning if it fails.
NOTE:
