What is Reliability Testing

Let’s see, What is Reliability Testing.

Software’s reliability is a measure of stability and overall performance of a software collated during an extended period of time under various specific sets of test conditions“.

This type of testing incorporates the results from non-functional testing such as stress testing, security testing, network testing, along with functional testing.  It is a combined metric to define a system’s overall reliability.

A measure of reliability should be defined by business requirements in the form of service levels.  These requirements should then be used to measure test results and the overall reliability metric of a system under test.


Reliability Testing

According to ANSI, Software Reliability is defined as the probability of failure-free software operation for a specified period of time in a specified environment. Software Reliability is not a direct function of time.

Electronic and mechanical parts may become “old” and wear out with time and usage, but the software will not rust or wear out during its life cycle. The software will not change over time unless intentionally changed or upgraded.


Software reliability is a key part in software quality. The study of software reliability can be categorized into three parts:

1. Modeling : Software reliability modeling has matured to the point that meaningful results can be obtained by applying suitable models to the problem. There are many models exist, but no single model can capture a necessary amount of the software characteristics. Assumptions and abstractions must be made to simplify the problem. There is no single model that is universal to all the situations.

2. Measurement : Software reliability measurement is naive. Measurement is far from commonplace in software, as in other engineering fields. “How good is the software, quantitatively?” As simple as the question is, there is still no good answer. Software reliability can not be directly measured, so other related factors are measured to estimate software reliability and compare it among products. The development process, faults and failures found are all factors related to software reliability.

3. Improvement : Software reliability improvement is hard. The difficulty of the problem stems from an insufficient understanding of software reliability and in general, the characteristics of software. Until now there is no good way to conquer the complexity problem of software. Complete testing of a moderately complex software module is infeasible. The defect-free software product can not be assured. Realistic constraints of time and budget severely limit the effort put into software reliability improvement.


Importance of Reliability Testing

As we now software applications are into use in almost every sector of manufacturing, health, and care, defense, government, telecommunication, etc. Therefore the question is that how reliable the software application is? This question is very important because the reliable software is of great use and the organization working on it can feel the confidence in their business systems. To verify the software reliability by reliability testing below measures are required:

  • Test cases should be designed covering all the required functionality of the software application and these test cases should be executed for sufficient amount of time to get a rough estimate of how long this software can execute fine without failure. The test should be executed for long duration to observe environment level failures like out of memory error, buffer overflows, database deadlocks, etc. which require time to show up.
  • The test case execution sequence to run the overall functionality of the software application should match the real production operational plan of the application. More often a function is executed; more is the percentage of test cases that should allocate that function or module of the software application.


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