CS135

Question 1

Define Software Engineering.

Answer 1

The application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software.

Question 2

What is the main goal of software engineering?

Answer 2

To deliver high-quality software that is functional, secure, maintainable, and meets deadlines and budgets.

Question 3

Explain why maintenance cost is a major concern in SE.

Answer 3

More than 50% of lifecycle costs are due to maintenance, making understandability and documentation crucial.

Question 4

What are the typical documents produced in the Waterfall Model?

Answer 4

Requirements, Specification, Design Documents, User Manuals, Test Data, and Evaluation Reports.

Question 5

Explain the difference between black-box and white-box testing.

Answer 5

Black-box testing is based on specification; white-box testing is based on internal code structure.

Question 6

What does JUnit automate?

Answer 6

Test execution and evaluation.

Question 7

What is meant by ‘Design by Contract’ in Dafny?

Answer 7

A method specifies its required inputs (preconditions) and guaranteed outputs (postconditions).

Question 8

Describe Boundary Value Analysis (BVA) and when it is useful.

Answer 8

A black-box technique focusing on the edges of input domains, useful for catching off-by-one errors.

Question 9

What are the five typical input values used in BVA?

Answer 9

min, min+, nom, max-, max

Question 10

What is an equivalence class in software testing?

Answer 10

A subset of inputs that the system treats the same; testing one value from each is often sufficient.

Question 11

What are the components of a test case?

Answer 11

Name, input(s), expected result, and actual result (for evaluation).

Question 12

When can a test suite be called minimal?

Answer 12

When no test case can be removed without reducing its coverage.

Question 13

Define C0, Cp, and Ci(k) coverage criteria.

Answer 13

C0: statement coverage; Cp: branch coverage; Ci(k): loop coverage up to k iterations.

Question 14

How does Ci(2) work in loop testing?

Answer 14

It checks loop behavior for 0, 1, and 2 iterations.

Question 15

Why is complete testing impossible?

Answer 15

The input space is often too large to test every possible case (e.g., for ints: billions of values).

Question 16

Compare testing vs program verification.

Answer 16

Testing samples input space; verification (e.g. Dafny) symbolically proves correctness for all inputs.

Question 17

What is a weakest precondition (WP)?

Answer 17

The least restrictive condition under which a statement guarantees a postcondition.

Question 18

Explain loop invariants in Dafny.

Answer 18

Conditions that must hold before and after every loop iteration; essential for correctness proofs.

Question 19

What does the keyword ‘assert’ do in Dafny?

Answer 19

Checks a condition at a point in code; if it fails, verification stops.

Question 20

How is substitution used in WP calculations?

Answer 20

To replace variables with expressions in postconditions to compute preconditions.

Question 21

What replaces specifications in Extreme Programming (XP)?

Answer 21

Tests that define the system’s expected behavior.

Question 22

What are XPs coding principles?

Answer 22

Write tests first; perform 10-minute builds; frequent integration.

Question 23

What is a ‘story’ in XP?

Answer 23

A small, user-visible feature or functionality unit.

Question 24

What is the advantage of pair programming in XP?

Answer 24

Improved code quality and shared knowledge through constant peer review.

Question 25

What does Checkstyle do?

Answer 25

Automatically checks Java code for compliance with style guidelines.

Question 26

Give a rule for commenting loops.

Answer 26

Explain the loops purpose, computation, and termination condition.

Question 27

What is the order of items in a Java class file?

Answer 27

Class comment, class statement, public/protected/private variables, constructors, methods.

Question 28

Why is readability important in code?

Answer 28

Improves maintainability and reduces the chance of introducing bugs.

Question 29

What is a node with outdegree 0 called?

Answer 29

A terminal node.

Question 30

Define a branch in a control flow graph.

Answer 30

An edge (a, b) is a branch if there is another edge (a, c) with b = c.

Question 31

What is a cycle in a graph?

Answer 31

A path that starts and ends at the same node.

Question 32

What is a test oracle?

Answer 32

The source (e.g., specification) used to determine the expected output of a test case.

Question 33

Name two typical Javadoc tags.

Answer 33

@param and @return

Question 34

Give an example of a Dafny contract.

Answer 34

requires x >= 0; ensures result == x * x

Question 35

Why might you use symbolic AI in verification?

Answer 35

To reason about all possible inputs and states instead of testing finite cases.

Question 36

What is the IEEE definition of Software Engineering?

Answer 36

Software Engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software.

Question 37

What was the original context of the term 'Software Engineering'?

Answer 37

Introduced as a provocation at NATO workshops in 196869 to emphasize the need for engineering principles in software development.

Question 38

List typical parts of a software product aside from code.

Answer 38

Requirement documents, design documents, user manuals, and test plans.

Question 39

Why is software considered intangible compared to physical engineering?

Answer 39

Software lacks physical constraints, which increases design freedom but also complexity.

Question 40

List five goals of Software Engineering.

Answer 40

Correctness, maintainability, usability, efficiency, and reliability.

Question 41

What does the 'Software Quality Crisis' refer to?

Answer 41

Verification and validation costs surpass the cost of coding itself.

Question 42

How is Software Engineering interdisciplinary?

Answer 42

It intersects with computer science, management, psychology, economics, and law.

Question 43

What is meant by a 'software lifecycle'?

Answer 43

The stages software passes through from initial concept to retirement, typically modeled in SDMs.

Question 44

Describe the phases of the Waterfall model.

Answer 44

Requirements Specification Design Implementation Testing Maintenance.

Question 45

What documents are produced in the design phase of the Waterfall model?

Answer 45

System architecture, user handbook, verification plan.

Question 46

What is the main difference between Spiral and Waterfall?

Answer 46

Spiral allows iterative refinement and risk analysis; Waterfall is strictly linear.

Question 47

What question does a Software Development Model answer?

Answer 47

What shall we do next? How long shall we continue to do it?

Question 48

What is a 'story' in XP?

Answer 48

A small unit of customer-visible functionality replacing formal requirements.

Question 49

How does XP handle system specifications?

Answer 49

By writing tests that define the system's intended behavior instead of documentation.

Question 50

List three coding principles in XP.

Answer 50

Write tests first, frequent integration, 10-minute builds.

Question 51

Contrast V-model testing with Agile testing.

Answer 51

V-model ties each dev phase to a corresponding test phase, while Agile integrates testing continuously.

Question 52

What are advantages of Agile over traditional models?

Answer 52

Fewer documents, higher flexibility, customer feedback throughout.

Question 53

What is the goal of whitebox testing?

Answer 53

To ensure all internal structures of the code are properly tested.

Question 54

Define C0 coverage.

Answer 54

C0 ensures every line of code (node in control flow graph) is executed at least once.

Question 55

Define Cp coverage.

Answer 55

Cp ensures every branch (decision outcome) is executed at least once.

Question 56

Define Ci(k) coverage.

Answer 56

Tests loops for 0, 1, ..., k iterations to ensure looping behavior is exercised.

Question 57

Why might a C0 test suite not detect certain bugs?

Answer 57

It may execute all code paths but miss incorrect logic in alternate branches.

Question 58

How is a control flow graph constructed?

Answer 58

Nodes represent code statements or conditions; edges represent transitions.

Question 59

What is a minimal test suite for a coverage criterion?

Answer 59

A set of tests that satisfies the criterion using the fewest test cases possible.

Question 60

Give an example where Ci(2) testing is useful.

Answer 60

Testing nested or compound loops to ensure correctness under repetition.

Question 61

What is the goal of blackbox testing?

Answer 61

To validate software behavior against the specification without internal knowledge.

Question 62

Describe the process of Boundary Value Analysis.

Answer 62

Identify input boundaries and test at, just above, and just below them.

Question 63

What types of errors does BVA target?

Answer 63

Off-by-one and boundary-related logic faults.

Question 64

Define weak normal equivalence class testing.

Answer 64

Select one test from each equivalence class for each input variable.

Question 65

Define strong normal equivalence class testing.

Answer 65

Test all combinations of equivalence classes of inputs.

Question 66

How are equivalence classes derived?

Answer 66

Based on the output behavior implied by the input domains.

Question 67

When would strong equivalence testing be preferred over weak?

Answer 67

When high reliability is needed or input variable interactions are complex.

Question 68

What is robustness testing?

Answer 68

Extends BVA by testing outside valid input ranges to evaluate failure modes.

Question 69

What is Dafny?

Answer 69

A verification-aware language that uses contracts to ensure correctness.

Question 70

Define a Dafny contract.

Answer 70

A combination of 'requires' (precondition) and 'ensures' (postcondition).

Question 71

How does Dafny differ from traditional testing?

Answer 71

It uses symbolic reasoning to prove correctness for all valid inputs.

Question 72

What is a weakest precondition?

Answer 72

The minimal condition that must be true before a statement to ensure a postcondition.

Question 73

What does 'assert' do in Dafny?

Answer 73

It checks that a condition holds at a specific program point.

Question 74

What are loop invariants?

Answer 74

Conditions that remain true before and after every iteration of a loop.

Question 75

Give a rule to compute WP for sequential composition.

Answer 75

WP[S;T,Q] = WP[S, WP[T,Q]]

Question 76

Explain the benefit of using ghost variables.

Answer 76

Used for reasoning in proofs without affecting compiled code.

Question 77

What is the purpose of code formatting?

Answer 77

Improve readability and maintainability.

Question 78

What is the role of Checkstyle?

Answer 78

A tool that enforces coding style guidelines.

Question 79

List two rules for method formatting in Java.

Answer 79

Braces on same line, blank line between methods.

Question 80

Why should variable declarations be commented?

Answer 80

To explain their role in the context of the program.

Question 81

What should comments on loops explain?

Answer 81

Purpose, computation process, and termination.

Question 82

What is the problem with over-commenting?

Answer 82

It adds noise without value, e.g., trivial comments.

Question 83

Differentiate between stack and queue.

Answer 83

Stack is LIFO; Queue is FIFO.

Question 84

What does the 'errorFree' flag in a stack do?

Answer 84

Indicates whether any unsafe stack operations occurred.