which has highest probability of finding the defect.

Designing good test cases is a complex art. The complexity 
comes from three sources. Test cases help us discover 
information. Different types of tests are more effective 
for different classes of information. Test cases can 
be "good" in a variety of ways. No test case will be good 
in all of them. People tend to create test cases according 
to certain testing styles, such as domain testing or risk-
based testing.

a good test case is one that discovers as many as not yet 
discovered errors or bugs.

a successful test case is one that is successful to find 
the desired bug

A Good test mean how many defect are covering with that 
test cases.

GOOD TESTCASE IS ONE THAT HAS HIGHEST PROBABILITY OF 
DETECTING UNDISCOVERED ERRORS.

A good testcase means which has high probability of finding 
on error in the developed system.

A test case is written to check the positive flow of the 
application
If we find more number of errors for a single test case 
written then that test case can be called as aGOOD TEST 
CASE because we are covering the maximun flow with that 
written test case

it should be smple understandable & powerfull mean should 
not have diffects