52'357 Software Correctness

1
52.357 Software Correctness

• Functional Testing

2
Functional Testing Methods

• Equivalence Partitioning
• Boundary-value analysis
• Cause-effect graphing
• Category Partition analysis

3
Specification for Testing

• The program prompts the user for a positive
  integer in the range 1 to 20 and then reads in a
  series of characters of this size.The program
  then prompts for a character and returns the
  position in the string at which the character was
  first found or an error message. The user can now
  repeat the operation.

4
Equivalence Partitioning (EP)

• Divide the input domain into classes of data
  which can be treated identically by the program.
• Also Invalid data.
• Output domain as well as input domain should be
  considered.
• Note Classes must be complete distinct.

5
EP Application

• 4 inputs positive integer, series of characters,
  searching character, more searches?
• Positive integer - range 1 to 20, Hence
• one class in range
• two either side of range

6
EP Application

• Series of characters - no information given hence
  no more classes
• Searching character - all characters to be
  treated identically
• more searches? - yes and no (2 classes)

7
EP Application

• Output side
• position or error (not found)
• Given these classes now construct a set of test
  cases
• Hint you should have 4

8
Boundary Value Analysis

• Add on to EP
• Looks at EP class boundaries
• just inside
• on the boundary
• just outside

9
BVA - Examples

• For a range of values bounded by a and b, test
  (a-1), a, (a1), (b-1), b, (b1).
• If input conditions specify a number of values
  n, test with (n-1), n and (n1) input values.

10
BVA - Examples

• Apply previous examples to output conditions
  (e.g., generate table of min and maxi size).
• If internal program data structures have
  boundaries (e.g., buffer size, table limits), use
  input data to exercise structures on boundaries.

11
BVA - Application

• Apply BVA to our EP classes on the sample
  problem and generate those test cases ..
• Hint You should now have 6 cases.

12
Cause-Effect Graphing

• Cause-effect graphing attempts to provide a
  concise representation of logical combinations
  and corresponding actions.
• For example effect 10 occurs if both causes 1
  and 2 exist
• in other words, 1 and 2 -gt 10

13
Cause-Effect Graphing

• Causes (input conditions) and effects (actions)
  are listed for a module and an identifier is
  assigned to each.
• A cause-effect graph developed.
• Graph converted to a decision table.
• Decision table rules are converted to test
  cases.

14
CEG -Application

• Causes
• integer in range 1 to 20
• searched for character
• Another search?

15
CEG - Application

• Effects
• Integer out of range
• character found (position)
• error message
• Program terminates

16
CEG - App Decision Table

• 1 1011-
• 2 -10-
• 3 -110
• A 1000
• B 0100
• C 0010
• D 0001