05 Software Testing and Validation

Question 1

What are test cases

Answer 1

description of a set of actions performed on software and expected outcome

Question 2

what are tests

Answer 2

1. execution of test case

2. produces outcome

Question 3

what is Testing

Answer 3

practice of creating, maintaining, executing, evaluating test cases

Question 4

What is software testing

Answer 4

1. process to execute program using data to simulate user input
2. process of locating, identifying bugs before delivery to user
3. part of general verification and validation

Question 5

what are program testing goals

Answer 5

1. demonstrate to stakeholders that software meets requirements
2. discover which behaviour is incorrect, undesirable, does not conform to specifications

Question 6

What is a “good” test

Answer 6

1. high probability of finding error
2. neither too simple nor complex
3. not redundant
4. detect maximum number of errors

Question 7

How to ensure accuracy of software

Answer 7

1. verification
   - check consistency of an output of software with its input
2. validation
   - assess how software fulfills its requirement
3. defect testing
   - discover faults in software that does not conform with specification

Question 8

verification examples

Answer 8

1. is the software built right
2. does software meets functionality
3. takes place first
4. goal: application and architecture
5. static activities
6. use reviews and walkthroughs

Question 9

validation examples

Answer 9

1. are we building the right product
2. does functionality meet intended behaviour
3. after verification
4. goal: actual product
5. dynamic activities and execution of code
6. use black/white box testing, nonfunctional test

Question 10

static analysis

Answer 10

inspection:

1. requirement specification
2. architecture
3. UML design
4. database schema
5. program
6. unable to check nonfunctional such as performance and usability

Question 11

dynamic analysis

Answer 11

testing:

1. exercising
2. observing product behaviour

Question 12

static/dynamic testing differences

Answer 12

static

1. find bug without code execution
2. verification stage
3. cost effective
4. done with reviews, walkthroughs, inspections

dynamic

1. execute code to find result
2. validation stage
3. expensive
4. done with unit, system, integration tests

Question 13

software testing process

Answer 13

1. design test cases
2. prepare test data
3. run program with test data
4. compare result to test cases

inputs: preconditions
expected: post conditions, actual output

Question 14

stages of testing

Answer 14

1. development testing
   - unit test
   - integration test
   - system test
2. release testing
   - separate testing team test before release to user
3. user test
   - customer test solution on their own environment

Question 15

debugging process

Answer 15

1. identify problems
2. identify cause of problems
3. fix problems
4. evaluate solution

Question 16

error handling approaches

Answer 16

1. ignore
2. failfast
   - program stops immediately, reports error
3. failsafe
   - program acknowledges error
   - continues execution in best way possible

Question 17

ideal test policies

Answer 17

exhaustive testing

• test all possible scenarios
• impractical but not impossible
• need testing techniques for wide coverage without exhaustive testing

Question 18

test driven development

Answer 18

1. write test cases before writing code
2. run code with test
3. move to next increment after test case passes

Question 19

benefits of TDD

Answer 19

1. code coverage
   - all code pass at least one test
2. regression testing
   - test is developed incrementally with code
3. simplified debugging
   - if code fails, only newly written code needs to be checked
4. system documentation
   - test act as a form of documentation

Question 20

black box testing

Answer 20

1. functionality testing
2. based solely on analysis of requirements
3. without knowing internal codes
4. can be applied to every level of testing
5. able to detect
   - incorrect functions
   - interface error
   - usability problem
   - concurrency and timing
   - data structure/db access

Question 21

white box testing

Answer 21

1. structured test
2. based on analysis of internal logic
3. compared with expected results

Question 22

advantages of black box testing

Answer 22

1. unbiased as tester is not developer

Question 23

black box testing disadvantages

Answer 23

1. unnecessary testing
   - different way to test the same thing
2. insufficient testing
   - miss out corner cases