02-12 (tutorial on testing)

Tutorial

• always initialize pointers to NULL when declaring them!
• always initialize the value of the pointer after you allocate it (if you need to)
• always check if there is enough memory. calloc returns NULL if there’s no memory.
  • In the assignment there WILL be test cases for memory and null pointers.
  • So check for null pointers everywhere and anywhere, all of the time.

Testing

• Test functions b4 using them. If all the individual functions work then you good.
  • I.e. if function B uses A and B isn’t working, it could be A that is wrong.
• Test:
  • Reasonable inputs
  • Unexpected inputs (i.e. NULL)
• Every test should identity the corresponding correct result.
  • You can’t test something you don’t know what it would do.

Exercise time:

• test findPrimes first

Test Case	Input	Expected Output	How to Check
Array of size 0	a pointer to an array of size 0	an empty array	Read over and check
Array of size 1	—	[2]	| | |
Array of size 100		An array of 100 prime numbers	| | |
Array of size 1000		1000 prime numbers	| | |

• then lastDigit

Test Case	Input	Expected Output	How To Check
1 digit	0	0	Read over and check
medium length	102	2	| | |
long length	11111133	3	| | |
negative numbers	-12	2	| | |
-	-1	1	| | |
-	-123456789	9	| | |

• then countDigits

Test Case	Input	Expected Output	How To Check
array is size 0	[]	counts should be empty	Read over and check
array is size 1	[131]	count should be [0,1,0,0,0,0,0,0,0,0]	| | |
array is medium	[1,2,3,4,5,6,7,8,9]	count should be [0,1,1,1,1,1,1,1,1,1]	| | |
array is big	[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]	count should be [1,2,2,2,2,2,2,1,1,1]	| | |