Structural testing

Question 1

Whats a chain

Answer 1

chain:
sequence of nocdes where each node:
has exctly one indegree and one out degree
every two consecutive nodes in that sequence has an edge between them

Question 2

What is structural testing

Answer 2

testing that uses program structure (e.g., flow graphs) to measure test adequacy and identify gaps in test sets.

Question 3

finite feasible

Answer 3

• A coverage criterion is finitely feasible if a finite test suite can satisfy it by covering all reachable required elements (nodes, edges, etc.).

Question 4

is all nodes always finitely feasible read

Answer 4

No, it is not always guaranteed to be finitely feasible. The all-nodes coverage criterion is only finitely feasible when restricted to reachable nodes. Programs may contain dead code, making some nodes unreachable. Determining whether a node is reachable in general reduces to the halting problem, which is undecidable, so reachability itself is undecidable. Therefore, all-nodes coverage is only finitely feasible when limited to reachable nodes.

Question 5

Advantages of structural

Answer 5

• Pros:
  
  • Directly examines program structure.
  • Detects gaps in test coverage (e.g., untested statements or paths).
  • Can improve reliability by covering critical structural components.

Question 6

Disadvantages of structural

Answer 6

• Cons:
  
  • Relies on program implementation (not specifications).
  • May miss functional requirements or logical errors

Question 7

What is regression testing

Answer 7

Testing that ensures new changes do not break existing working functionality.

Question 8

Purpose of regression testing

Answer 8

1. New code changes have not introduced defects into previously working functionalities.
   
   2. The system continues to behave as expected after updates.

Question 9

When regression testing

Answer 9

When is Regression Testing Performed?

1. After Bug Fixes:
   
   • To ensure the fix doesn’t affect unrelated parts of the application.
2. After Feature Additions or Enhancements:
   
   • To confirm that new functionality integrates seamlessly with existing code.
3. After Refactoring:
   
   • To validate that code improvements (e.g., performance optimizations) haven’t introduced errors.
4. Before Major Releases or Updates:
   
   • To verify that the application as a whole is stable.

Question 10

How regression testing works

Answer 10

1. Create a Regression Test Suite:
   
   • A collection of test cases covering the application’s core functionalities, edge cases, and previously reported bugs.
2. Execute Tests:
   
   • Run the suite after every significant change.
   • Automated tools are commonly used to speed up this process.
3. Analyze Results:
   
   • Compare current results with expected outputs.
   • Investigate and fix any discrepancies.

Question 11

Name 3 techniques in regression testing as well as pros and cons

Answer 11

1. Retest All:
   
   • Run all existing test cases, including functional and non-functional tests.
   • Pros: Comprehensive coverage.
   • Cons: Time-consuming and resource-intensive.
2. Selective Testing:
   
   • Identify and execute only the test cases related to the changed areas.
   • Pros: Efficient and faster than retesting all.
   • Cons: May miss indirect effects of changes.
3. Prioritized Testing:
   
   • Prioritize tests based on the criticality of features and modules.
   • Example: Core banking transactions in a banking application.
4. Automated Regression Testing:

Question 12

Why regression testing important

Answer 12

Why is Regression Testing Important?

1. Prevents Bugs in Production:
   
   • Ensures that new code changes do not cause unexpected issues.
2. Maintains Stability:
   
   • Helps preserve the quality and reliability of software as it evolves.
3. Increases Confidence:
   
   • Provides assurance that changes are safe and the application is ready for deployment.
4. Supports Continuous Development:
   
   • Essential in Agile and DevOps practices where frequent updates are common.

Question 13

challenges with regression

Answer 13

Challenges in Regression Testing

1. Time-Consuming:
   
   • Running a full test suite can take a significant amount of time.
2. Costly for Large Systems:
   
   • Large codebases require extensive test case management and execution.
3. False Positives/Negatives:
   
   • Improperly maintained test cases may yield inaccurate results.
4. Automation Maintenance:
   
   • Automated regression tests must be updated to align with application changes.

Question 14

Whats a maximal chain

Answer 14

maximal chain: a chain such that adding any other adjacent node would make it lose its property of being a chain

Question 15

What is a dd path

Answer 15

a dd path is a set of that is either :
. a single node ( start or terminal)
. special node ( branching node - outdegree is >=2 or merging node - indegree is >=2 )
. a maximal chain

EACH NODE BELONGS TO EXACTLY ONE DD PATH

Question 16

What is a dd path graph

Answer 16

A DD-path graph is obtained from the original control-flow graph (CFG) by:

Collapsing each maximal chain into a single node, and

Keeping all start, terminal, branch, and merge nodes as single nodes, and

Preserving the control-flow edges between these new nodes.

Question 17

When is dd path graph adequate

Answer 17

for each node or edge in dd path graph theres a test case covering it

Question 18

READ VERY IMPORTANT

Answer 18

dd path coverage is equivalent to edge coverage BUT REQUIRES LESS CHECKS

This is because we group maximal chains into one unit

Question 19

Read very important

Answer 19

dd path coverage subsumes node coverage because:
each node belongs to exactly one dd path so if you have full dd path coverage you have full node coverage

Question 20

is dd path coverage complete ?

Answer 20

dd path coverage:
Not complete ( no gurantee all bugs found)

solution:

use stronger adeqiacy criterial ( prime paths…) -> However problem with this is that it leads to more test cases and no guarantee that more bugs will be found -> tradeoff between potential reward of stronger adequacy and expensiveness to implement this stronger critera

another solution you can do is you switches ( or if elses) instead of sequential condtions to reduce risk of bugs

Question 21

What is a simple path

Answer 21

simple path - path that visits A node at most once ( except potentially start and end)

tip : no repetition except potentially start and end

Question 22

what is a prime path

Answer 22

prime path -
simple path that cannot be extended without losing its property of being simple path

Question 23

what is adequacy in prime paths

Answer 23

for each prime path there is a test case that covers it

Informally -
test case covers every simple path and up to two iterations of a loop

Question 24

cyclomatic number

Answer 24

the no of linearly independent paths in a programs control flow graph

Question 25

very important just read

Answer 25

cyclomatic number - take one path from start to exit , counting number of alternatives by flipping condition one at a time does a shoter or longer program have higher cyclomatic: longer has higher as it is more likely to have more independent decision points ( if , while , for , case ...) Longer program more likely to have more of these ( branches , loops...) and so has higher cyclomatic

Question 26

tip for cyclometric BEST

Answer 26

No of regions in plane ONLY IF : connected graph one start and one terminal

Question 27

tip for cyclometric

Answer 27

E - N + 2 ONLY IF : connected graph one start and one terminal

Question 28

what does a high cyclometric tell you

Answer 28

impossible to test program

Question 29

Advantage of cyclometric

Answer 29

.Tells you how testable your program is . gives the number of linearly independent paths in control-flow graph and therefore tells us the minimum number of test cases required to achieve basis path coverage.