SixthSetOf10Questions Flashcards
What are the reasons that humans make errors?
- time pressure
- complexity of work products,
- processes,
- infrstructure or interactions
- or because they are tired or lack adequate training
Where can be defects found?
can be found in documentaation such as
requriements specifications or a test script,
- in source code
- or in a supporting artifact such as a build file
What happens if there are defects ?
Defects in artifacts that were produced earlier in the SDLC, if undetected, often lead to defective artifacts later in the lifecycle.
If a defect in code is executed, the system may fail to do what it should do,
or it may do something it shouldn’t do, hence causing a failure.
Some defects will always result in a failure if executed, while others will only result in a failure in specific circumstances, and some may never result in a failure
What are the causes for failures?
Errors and defects are not the only cause of failures. Failures can also be caused by environmental conditions, such as when radiation or electromagnetic field cause defects in firmware.
What are root causes?
A root cause is a fundamental reason for the occurrence of a problem (e.g., a situation that leads to an error). Root causes are identified through root cause analysis, which is typically performed when a failure occurs or a defect is identified. It is believed that further similar failures or defects can be prevented or their frequency reduced by addressing the root cause, such as by removing it.
TESTING PRINCIPLES
What are the seven principles of testing?
- Testing shows the presence, not the absence of defects
- Exhaustive Testing is impossible
- Early testing saves time and money
- Defects cluster together
- Tests wear out
- Tsting is context dependent
- Absence-of-defects fallacy
What can we say about testing principle number one
Testin shows presence of defects, not absence of defects
- testing cannot prove that there no defects
- testing reduces the probability of defects, remaining
undiscovered in the test object,
- even if no defects are found, testing cannot prove object correctness
What can we say about testing principle number two?
Exhaustive testing is impossible:
- testing everything is not feasible
- rathen than attempting to test exhaustively,
test techniques, test case prioritization and risk-based testing should be used to focus test efforts.
What can we say about testing principle number three?
Early testing saves time and money
- Defects that are removed early in the process
will not cause subsequet defects in derived work
products
- the cost of quality will be reduced since fewer failures
will occur later in SDLC .
- to find defects early, both static testing and dynamic testing should be started as early as possible
What can we say about the fourth principle ‘Defects Cluster Together’?
- a small number of system components usually
contain most of the defects discovered - or are responsible for most of the operational failures
- this phenomenon is an illustration of the Pareto principle
- Predicted defect clusters, and actual defect clusters observed during testing or in operation are an important
input for risk-based testing.
