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Performance testing

Not all software systems have specifications on performance explicitly. But every system will have implicit performance requirements. The software should not take infinite time or infinite resource to execute. "Performance bugs" sometimes are used to refer to those design problems in software that cause the system performance to degrade.

Performance has always been a great concern and a driving force of computer evolution. Performance evaluation of a software system usually includes: resource usage, throughput, stimulus-response time and queue lengths detailing the average or maximum number of tasks waiting to be serviced by selected resources. Typical resources that need to be considered include network bandwidth requirements, CPU cycles, disk space, disk access operations, and memory usage. The goal of performance testing can be performance bottleneck identification, performance comparison and evaluation, etc. The typical method of doing performance testing is using a benchmark - a program, workload or trace designed to be representative of the typical system usage.

Security testing

Software quality, reliability and security are tightly coupled. Flaws in software can be exploited by intruders to open security holes. With the development of the Internet, software security problems are becoming even more severe.

Many critical software applications and services have integrated security measures against malicious attacks. The purpose of security testing of these systems include identifying and removing software flaws that may potentially lead to security violations, and validating the effectiveness of security measures. Simulated security attacks can be performed to find vulnerabilities.

Testing automation

Software testing can be very costly. Automation is a good way to cut down time and cost. Software testing tools and techniques usually suffer from a lack of generic applicability and scalability. The reason is straight-forward. In order to automate the process, we have to have some ways to generate oracles from the specification, and generate test cases to test the target software against the oracles to decide their correctness. Today we still don't have a full-scale system that has achieved this goal. In general, significant amount of human intervention is still needed in testing. The degree of automation remains at the automated test script level.

The problem is lessened in reliability testing and performance testing. In robustness testing, the simple specification and oracle: doesn't crash, doesn't hang suffices. Similar simple metrics can also be used in stress testing.

When to stop testing?

Testing is potentially endless. We can not test till all the defects are unearthed and removed - it is simply impossible. At some point, we have to stop testing and ship the software. The question is when.

Realistically, testing is a trade-off between budget, time and quality. It is driven by profit models. The pessimistic, and unfortunately most often used approach is to stop testing whenever some, or any of the allocated resources - time, budget, or test cases - are exhausted. The optimistic stopping rule is to stop testing when either reliability meets the requirement, or the benefit from continuing testing cannot justify the testing cost. This will usually require the use of reliability models to evaluate and predict reliability of the software under test. Each evaluation requires repeated running of the following cycle: failure data gathering - modeling - prediction. This method does not fit well for ultra-dependable systems, however, because the real field failure data will take too long to accumulate.

Questions & Answers

The following text is encoded in base 64. Ik5ldmVyIHRydXN0IGEgY29tcHV0ZXIgeW91IGNhbid0IHRocm93IG91dCBhIHdpbmRvdyIgLSBTdGV2ZSBXb3puaWFr Decode it, and paste the decoded text here
Julian Reply
what to do you mean
Vincent
What is the command to list the contents of a directory in Unix and Unix-like operating systems
George Reply
how can i make my own software free of cost
Faizan Reply
The name of the author of our software engineering book is Ian Sommerville.
Doha Reply
what is software
Sampson Reply
the set of intruction given to the computer to perform a task
Noor
I want to know about prototype model in software engineering
Malli Reply
Prototype Model is a replica model. In this we plan and build a rough application. Further we launch it for users and if they give their feedback or need any enhancement then we add-on requested features as per the system/user requirements.
KUMAR
between JavaScript and html,which is the best to master first?
Njuguna Reply
You have to master HTML first before you do javascript. Actually Html is not a programming language it is used to make a skeleton of a webpage
Alfayo
yaah it so good to start with HTML first
Abel
what is a software
Carren Reply
I am not proficient in any programming language though I am learning python currently, is it necessary to be proficient in programming language before one can undergo this course
Israel Reply
what is software
Arwaz Reply
The reason it all exists
Ruth Reply
Hi
Md
hlo
Ajay
Hii
Biddika
hu
Ajay
what is programming
Nonny Reply
software project scheduling
DEVENDRA Reply
kis chij ka bro
shiv
Green chili
Arwaz
wellcome my friend
my
what is soft ware
my
the soft ware of education
my
hello
Hilal
I'm new here
Hilal
how to communicate with clients
adejoh Reply
hey hi good afternoon sir my name is Mohamed Kamara, I want to understand how to do it sir.
Muhammadosman
ok
Ronald
how are u sir, I want u to teach me please I want to know about softwares.
Muhammadosman
me too I need this knowledge
anthony
me too
Noor
what's up y'all..who is good at java? need help
Adrian
Is it like a unit in software engineering or what?
Njuguna
Which SDLC Model will you select to develop the system as a software engineer and why?
Subrato Reply

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Source:  OpenStax, Software engineering. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10790/1.1
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