Reliability Testing

Reliability Testing
While developing a software product, there are various aspects and features of the software that are validated by the software engineers. Software reliability, which is a key to delivering a quality product to the users, is one such aspect that is verified and validated by the team with the assistance of reliability testing. Therefore, to help you comprehend the importance of reliability testing as well as product reliability, here is an exhaustive discussion on reliability testing.

What is Reliability Testing?

Software reliability testing is an important software testing technique that is performed by the team to ensure that the software is performing and functioning consistently in the given environmental conditions as well as in a specified period of time.

This testing process aids in measuring the overall reliability of the product, by testing it against the business requirements.

Reliability testing incorporates the results from both functional and non-functional testing, such as stress testing, security testing, functionality testing, production testing and more, which enables the team to determine various problems in the software design and functionality.

Objectives of Reliability Testing

To test the performance of software under a particular condition is the main the objective of Reliability testing.

  • To discover the perceptual structure of repetitive breakdown.
  • To find the numbers of failures, that occurs in a predetermined measure of time.
  • To locate the mean existence of the software.
  • To find the primary driver of failure.
  • Checking the execution of various units of programming in the wake of taking preventive actions.

Features of Reliability Testing:

The significance of reliability testing can further understood with the assistance of is various features, some of which are mentioned below:

  1. It can be defined as the ability of the software to work accurately under the given conditions.
  2. Reliability testing helps identify issues and faults in the software product, before it is delivered for the use of the end users.
  3. It ensures that the software meets the client’s as well as customer's reliability requirements.
  4. This type of testing is performed at various levels of software development, which further increases the reliability and dependability of the product.
  5. Reliability testing makes sure that the software is functioning without any defects and is working as per its intended purpose.
  6. It helps uncover issues and faults in the software design and functionality.
  7. In reliability testing, data is collected from various stages of software development.
  8. It is a important facet of reliability engineering program.

Factors Influencing Reliability Testing:

The process of reliability testing is influenced by few aspects, which impact the output delivered by this testing. Few of these factors are:

  • The number of issues and faults present in the system.
  • The way users operate the system.
  • Number of test executed by the team.

Reliability Testing Types:

The process of reliability testing can either be conducted manually or with the assistance of various available testing tools. Moreover, this testing incorporate three major types of reliability tests, which are described in detail below:

  • Feature Test: The purpose of features testing is to check the features as well as the functionality of the software product. During this type of testing, following aspects are ensured.
    • Every function needs to be executed at least once by the team.
    • The interaction between two or more function ought to be diminished.
    • Every function ought to execute completely.
    • Team should also check proper execution of each operation.
  • Regression Test: This testing is always done when new version or updating of software is build. Regression testing is required when the new function is added, and "old" function is removed and to check that no new bugs have been introduced in the application.
    • Verification of software quality as well as the accuracy of the new functionality added into the software product.
    • Detection of defects or bugs, which can be introduced in the system after the implementation of modifications or changes.
  • Load Test: This test is concluded to confirm the functionality of the software under the conditions of highest work load. Keeping in a mind to find the changing point of software, the abundance is step by step wider until the software gets Hung, breakdown, occupied and so on. At this edge, the application set accurately and anything from this point will give failure or lack of quality mode to an application.


Measurement plays a significant role in reliability testing. From calculating the probability of failure to evaluating the time of failure, Mean Time Between Failures (MTBF), and more, this type of testing provides information and evaluates various facets of the software product, which define its reliability. Hence, the formula used for this is:

Probability = Number of failed cases/Total number of cases under consideration

Moreover, the availability of the software is also measured in the terms of Mean Time Between Failures (MTBF), which further consists of mean time to failure (MTTF) and mean time to repair (MTTR). This is calculated with the assistance of the following formula:


Reliability Testing Approach:

The purpose of reliability testing is test the software system thoroughly to ensure that all the defects and faults in the system are identified and rectified by the team, before it is deployed to the user site. This is basically ensured with the assistance of following approaches:

  • Test-Retest Reliability: Here, the team tests and retests the software through various testing techniques to validate its reliability as well as dependability. This is done in a short span of time to check the stability and the consistency of the score.
  • Parallel Forms Reliability: During this approach the software is tested by two different groups simultaneously to test how similarly the two forms function. With this approach team is able to validate the consistency of the results across various forms.
  • Decision Consistency: Finally, the results from the test-retest reliability and parallel forms reliability are finally evaluated through this approach, which decides their success and failure.

Requirements of Reliability Testing:

Since software applications are now being used in various industries, testing and validating their reliability has gathered more significance, as it ensures high acceleration of revenue for businesses as well as higher software dependability. To make sure such results are achieved, it is vital for the team to consider various requirements of reliability testing, which are:

  • Test Cases ought to cover all the necessary functionality of the application and all these ought to be executed for an adequate measure of time for receiving the rough estimate of software >execution without any failure.
  • Such test ought to be executed for a long time as the spectator on the environment level of failure like buffer overflows, memory error, data base, deadlocks, etc. which need time to appear.
  • The sequence of test case should coordinate the genuine operational plan of the application. The more often function of the software is performed; more the benefits of test cases allocates the module and the function of a software application.
Since the importance of software reliability is increasing rapidly, it has become essential to perform reliability testing during SDLC. Though this type of testing is quite time and cost consuming, it is still vital to perform it, as it ensure validates the quality and the functionality of the software in various scenarios and ensures its accuracy.