Lecture 5

Question 1

What is a control flow graph?

Answer 1

It is a graph which describes the sequence in which the different instructions of a program get executed.

Question 2

What does an edge from one node to another represent in a CFG?

Answer 2

It represents the transfer of control between nodes

Question 3

How do you draw a CFG?

Answer 3

By knowing the sequence, selection and iteration statements

Question 4

What is a path?

Answer 4

It is a node and edge sequence from the starting node to a terminal node of the CFG. There can be more than one terminal node in a program.

Question 5

What does path coverage testing require?

Answer 5

Coverage of the linearly independent paths

Question 6

What is a linearly independent path?

Answer 6

Any path through the program that introduces at least one new edge that is not included in any other linearly independent paths.

Any path having a new node automatically implies that it has a new edge.

Question 7

Is a path that is a sub path of another path linearly independent?

Answer 7

No

Question 8

How do we determine the number of independent paths ?

Answer 8

By using McCabe’s cyclomatic complexity which finds the maximum number of linearly independent paths in a program. It doesn’t directly identify which paths or linearly independent but how many paths to look for and the minimum number of test cases required.

Question 9

What is McCabe’s Cyclomatic Complexity formula?

Answer 9

Edges - Nodes + 2 (E - N + 2)

OR

Decision statements + 1 (P+1)

Question 10

What steps should be followed for computing cyclomatic complexity and test cases design?

Answer 10

Construction of control flow graph (graph with nodes and edges from code)

Cyclomatic Complexity Calculation

Identification of the independent paths

Design of test cases

Question 11

What does it mean if the complexity number is between 1 and 10?

Answer 11

The code is structured and well written, it has high testability and the cost and effort is less.

Question 12

What does it mean if the complexity number is between 10 and 20?

Answer 12

The code is complex, it has medium testability and the cost and effort is medium

Question 13

What does it mean if the complexity number is between 20 and 40?

Answer 13

The code is very complex, it has low testability and the cost and effort is high

Question 14

What does it mean if the complexity number is over 40?

Answer 14

The code is not testable and it has very high cost and effort

Question 15

What are the software quality product and process metrics?

Answer 15

Defect Density
Code Coverage
Mean Time To Failure
Mean Time to Repair
Test Case Effectiveness
Customer Satisfaction
Cycle Time
Code Complexity

Question 16

What is defect density?

Answer 16

This measures the number of defects found in a software product per unit of size (lines of code). It can be used to evaluate the quality of the product and to identify areas for improvement.

Question 17

How do you calculate defect density?

Answer 17

Total number of defects/ size of the software product (LOC)

Question 18

What is code coverage?

Answer 18

The percentage of code that has been tested. It can be used to evaluate the thoroughness of testing and to identify areas of the code that haven’t been tested.

Question 19

How do you calculate code coverage?

Answer 19

(No. LOC executed / Total LOC) * 100

Question 20

What is mean time to failure?

Answer 20

The average time between failures of a software product. It can be used to evaluate the reliability of the product

Question 21

How do you calculate mean time to failure?

Answer 21

Total operating time/No. of failures

Question 22

What is mean time to repair?

Answer 22

The average time it takes to fix a defect in a software product. It can be used to evaluate the efficiency of the development process.

Question 23

How do you calculate mean time to repair?

Answer 23

Total downtime/ No. of repairs to restore operation

Question 24

What is test case effectiveness?

Answer 24

The percentage of test cases that detect defects. It can be used to evaluate the effectiveness of the testing process.

Question 25

How do we calculate test effectiveness?

Answer 25

(No of defects found/ total no of test cases executed) * 100

Question 26

What is customer satisfaction?

Answer 26

The satisfaction of customers with a software product. It can be obtained through surveys or feedback mechanisms and can be used to evaluate the overall quality of product.

Question 27

How do we calculate customer satisfaction?

Answer 27

(No of satisfied customers/ total number of respondents) * 100

Question 28

What is cycle time?

Answer 28

The time it takes to complete a software development process from start to finish. It can be used to evaluate the efficiency of the development process and to identify areas for improvement.

Question 29

How do you calculate cycle time?

Answer 29

Total processing time/ Total number of units

Question 30

What is code complexity?

Answer 30

The complexity of the code in a software product. It can be used to identify areas of the code that are difficult to maintain or modify.

Question 31

How do you calculate complexity?

Answer 31

McCabe’s Cyclomatic Complexity (No. edges - No. of nodes + 2)

Question 32

What is a state machine model?

Answer 32

An event driven model for a system whose processing behaviour are dependent on state transition.

Question 33

How are state machine models represented?

Answer 33

It is represented as states, events, actions and transitions.
State is the current situation
Event is the input to the state
Action is the activity to be performed
Transitions is the movement from one state to another

Question 34

What is a FSM quintuple?

Answer 34

Since FSMs are mathematical models used to represent the behaviour of a system that can be in one of a finite number of states. It is specified as a quintuple:

A is the finite input alphabet
Q is a finite set of states
q0 is the initial state
T is the state transition function
F is the finite set of final states