06 Software Testing and Validation

Question 1

black box testing approaches

Answer 1

1. equivalence partitioning
   - split input into partitions where values in each partition can be viewed as similar
2. boundary value analysis
   - for each partition, choose values at the boundary over those in the middle

Question 2

equivalence partitioning approach

Answer 2

1. number of possible test cases too large
2. partition input domain into equivalence classes where every element of a class is handled the same way
3. 2 test cases considered equivalent if program process them the same way
4. since test cases considered equivalent, we just need to test one element

Question 3

levels of partitioning

Answer 3

1. first level partitioning
   - valid vs invalid
2. 2nd level partitioning
   - smaller equivalence classes

Question 4

guidelines for selecting equivalence

Answer 4

1. range
   - 1 valid
   - 2 invalid
2. specific value
   - 1 valid
   - 2 invalid
3. member of a set
   - 1 valid
   - 1 invalid

create cartesian product to find number of test cases needed

Question 5

boundary value analysis

Answer 5

1. based on boundary conditions (corner cases)
2. greater number of errors occur at boundaries
3. complements equivalence partitioning approach

Question 6

guidelines for boundary value analysis

Answer 6

if boundary values are R1, R2 then
test R1-1, R1, R1+1, R2-1, R2, R2+1

Question 7

white box testing

Answer 7

1. aka structural, code based testing
2. test according to program structure
3. goal is to exercise all statements
4. have access to source codes
5. test base on coverage of
   - statement
   - branch
   - path
   - conditions
6. based on control flow graph

Question 8

control flow graph

Answer 8

1. shows flow of program statements
2. formed by nodes and edges
3. node: sequence of statements
4. edge: flow between nodes
5. decision nodes: node with multiple outgoing edges

Question 9

cyclomatic complexity

Answer 9

used to find no. of paths needed to cover all edges and nodes in CFG

3 ways to calculate:
1. number of enclosed regions in CFG
2. number of decision nodes + 1
3. edges - nodes + 2

Question 10

white box testing steps

Answer 10

1. draw CFG
2. calculate cyclomatic complexity number C
3. find the basis path set: at most C paths that cover all nodes and edges
4. design test cases to force execution along path in basis path set

Question 11

independent paths

Answer 11

1. an executable path through CFG from start node to the end node that has not been traversed before
2. must move along at least one edge that has yet to be traversed

Question 12

test coverage analysis

Answer 12

1. statement coverage = executed statements/ total statements
2. branch coverage = executed branch / total branch
   (branch = edges from decision nodes)
3. basis path coverage = tested path/ cyclomatic complexity number

Question 13

what is alpha testing

Answer 13

1. evaluate quality of software
2. tested by testers( not developers)
3. at developer site
4. comprise of both black and white box testing
5. reliability and security not tested in depth
6. does product work?

Question 14

what is beta testing

Answer 14

1. evaluate customer satisfaction
2. tested by end users
3. at client location
4. comprise of mostly black box tests
5. tested for reliability, security, robustness
6. do customers like the product?