Lecture1-Intro to software testing

Question 1

Why do we do software testing?

Answer 1

Software failures are costly and testing can help prevent these failures.

Question 2

What is the process of testing(4)?

Answer 2

Test Planning –> Test development–>Running test cases–>Evaluating test results

Question 3

Failure vs fault vs error

Answer 3

Error:
-A mistake usually made by PEOPLE.cause of a fault
Fault:
-The result of an error(BUG)
Failure:
-Occurs when the code corresponding to a fault executes. Observable incorrect behaviour of a program.

ERROR –>CAN LEAD TO –>FAULT –>CAN LEAD TO –>FAILURE

Question 4

What are the 3 levels of software testing?

Answer 4

1.Unit testing
2.Integration testing
3.System testing

Question 5

What is unit testing?

Answer 5

-Individual units(a function) are tested in isolation.
-Determine whether each unit functions as designed.

Question 6

What is integration testing?

Answer 6

-Test a group of related units together(testing database access)
-Find interface issues between units

Question 7

What is system testing?

Answer 7

-Test the complete software system
-Evaluate the system’s compliance with the specified requirements.

Question 8

What are the 2 basic approaches to identify test cases?

Answer 8

1.Black-box testing
2.White-box testing

Question 9

What is black-box testing?

Answer 9

-based on software description(specification)
-covers as much SPECIFIED behaviour as possible
-cannot reveal errors due to implementation details.

Question 10

What is white-box testing?

Answer 10

-based on the code
-covers as much CODED behaviour as possible
-cannot reveal errors due to missing paths

Question 11

What are the 4 QA approaches?

Answer 11

-Testing
-Static verification
-Inspection /review
-Formal proof

Question 12

Which QA approach has the most subjective bias?

Answer 12

Inspection/ review

Question 13

What does the testing approach consist of and what are its pros and cons (1 of each) ?

Answer 13

Exercising software to try and generate failures.
Pros: no false positives
Cons: incomplete

Question 14

What does the static verification approach consist of and what are its pros(1) and cons (2) ?

Answer 14

Identify specific problems statically considering all possible executions.
Pros: complete
Cons: false positive(main issue),expensive

Question 15

What does the inspection/review approach consist of and what are its pros(2) and cons (2) ?

Answer 15

Systematic group review of program text to detect faults.
Pros: systematic, thorough
Cons: informal, subjective

Question 16

What does the formal proof approach consist of and what are its pros (1)and cons (2) ?

Answer 16

Proving that the program text implements the program specification.
Pros: strong guarantees
Cons: complex, expensive (requires a specification)

Question 17

What is correctness?

Answer 17

-Do the specification and the program meet the customer/user’s expectations?
-Program P is correct with respect to specification S

*Test can never reveal the absence of a bug(fault).
*We run the program by running the code.

Question 18

What is validation ?

Answer 18

Process of evaluating software at the end of software development to ensure compliance with intended usage. => DO THE RIGHT THINGS

Question 19

What is verification?

Answer 19

The process of determining whether the products of a given phase of the software development process fulfill the requirements established during the previous phase=>DO THE THINGS RIGHT

Question 20

What is an example of validation vs verification?

Answer 20

Divide 2 numbers :

Validation : Does it divide ?
Verification: Is the division correct?

Question 21

Describe this process : Testing–>Test Failure–>Debugging

Answer 21

Testing: Evaluating software by observing its execution.
Test failure: Execution that results in a failure.
Debugging: The process of finding a fault given a failure.

Question 22

What are the three conditions that must be present for a failure to be observed (RIP)?

Answer 22

REACHABILITY : The location that contain the fault must be reached.
INFECTION: After executing the location, state of the program must be incorrect.
PROPAGATION:The infected state must propagate to cause some output of the program to be incorrect.

*Failure is a result of fault, but not all faults are a result of failure

Question 23

What is the content of a test case?(6)

Answer 23

-Summary
-Pre-conditions
-Inputs
-Expected outputs
-Observed outputs
-Pass/fail

Question 24

What is complete testing?

Answer 24

At the end of testing, you know there are no remaining unknown bugs.

Question 25

Why is complete coverage impossible?

Answer 25

-Domain of possible inputs is too large.
-Too many possible paths through the program.

Question 26

Bonus question : What do we categorize testing inheritance as (what level of testing, what approach) ?

Answer 26

Integration, white box