Lecture1-Intro to software testing Flashcards
Why do we do software testing?
Software failures are costly and testing can help prevent these failures.
What is the process of testing(4)?
Test Planning –> Test development–>Running test cases–>Evaluating test results
Failure vs fault vs error
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
What are the 3 levels of software testing?
1.Unit testing
2.Integration testing
3.System testing
What is unit testing?
-Individual units(a function) are tested in isolation.
-Determine whether each unit functions as designed.
What is integration testing?
-Test a group of related units together(testing database access)
-Find interface issues between units
What is system testing?
-Test the complete software system
-Evaluate the system’s compliance with the specified requirements.
What are the 2 basic approaches to identify test cases?
1.Black-box testing
2.White-box testing
What is black-box testing?
-based on software description(specification)
-covers as much SPECIFIED behaviour as possible
-cannot reveal errors due to implementation details.
What is white-box testing?
-based on the code
-covers as much CODED behaviour as possible
-cannot reveal errors due to missing paths
What are the 4 QA approaches?
-Testing
-Static verification
-Inspection /review
-Formal proof
Which QA approach has the most subjective bias?
Inspection/ review
What does the testing approach consist of and what are its pros and cons (1 of each) ?
Exercising software to try and generate failures.
Pros: no false positives
Cons: incomplete
What does the static verification approach consist of and what are its pros(1) and cons (2) ?
Identify specific problems statically considering all possible executions.
Pros: complete
Cons: false positive(main issue),expensive
What does the inspection/review approach consist of and what are its pros(2) and cons (2) ?
Systematic group review of program text to detect faults.
Pros: systematic, thorough
Cons: informal, subjective
What does the formal proof approach consist of and what are its pros (1)and cons (2) ?
Proving that the program text implements the program specification.
Pros: strong guarantees
Cons: complex, expensive (requires a specification)
What is correctness?
-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.
What is validation ?
Process of evaluating software at the end of software development to ensure compliance with intended usage. => DO THE RIGHT THINGS
What is verification?
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
What is an example of validation vs verification?
Divide 2 numbers :
Validation : Does it divide ?
Verification: Is the division correct?
Describe this process : Testing–>Test Failure–>Debugging
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.
What are the three conditions that must be present for a failure to be observed (RIP)?
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
What is the content of a test case?(6)
-Summary
-Pre-conditions
-Inputs
-Expected outputs
-Observed outputs
-Pass/fail
What is complete testing?
At the end of testing, you know there are no remaining unknown bugs.
Why is complete coverage impossible?
-Domain of possible inputs is too large.
-Too many possible paths through the program.
Bonus question : What do we categorize testing inheritance as (what level of testing, what approach) ?
Integration, white box
