Reliability Testing – Software Testing

Reliability Testing is a testing technique that relates to testing the ability of software to function and given environmental conditions that help in uncovering issues in the software design and functionality. This article focuses on discussing Reliability testing in detail.

What is Reliability Testing?

Reliability testing is a type of software testing that evaluates the ability of a system to perform its intended function consistently and without failure over an extended period.

1. Reliability testing aims to identify and address issues that can cause the system to fail or become unavailable.
2. It is defined as a type of software testing that determines whether the software can perform a failure-free operation for a specific period in a specific environment.
3. It ensures that the product is fault-free and is reliable for its intended purpose. 
4. It is an important aspect of software testing as it helps to ensure that the system will be able to meet the needs of its users over the long term.
5. It can also help to identify issues that may not be immediately apparent during functional testing, such as memory leaks or other performance issues.

The study of reliability testing can be divided into three categories:-

1. Modelling
2. Measurement
3. Improvement

Different Ways to Perform Reliability Testing

1. Stress testing: This testing involves subjecting the system to high levels of load or usage to identify performance bottlenecks or issues that can cause the system to fail
2. Endurance testing: Endurance testing involves running the system continuously for an extended period to identify issues that may occur over time
3. Recovery testing: Recovery testing is testing the system’s ability to recover from failures or crashes.
4. Environmental Testing: Conducting tests on the product or system in various environmental settings, such as temperature shifts, humidity levels, vibration exposure or shock exposure, helps in evaluating its dependability in real-world circumstances.
5. Performance Testing: It is possible to make sure that the system continuously satisfies the necessary specifications and performance criteria by assessing its performance at both peak and normal load levels.
6. Regression Testing: After every update or modification, the system should be tested again using the same set of test cases to help find any potential problems caused by code changes.
7. Fault Tree Analysis: Understanding the elements that lead to system failures can be achieved by identifying probable failure modes and examining the connections between them.

It is important to note that reliability testing may require specialized tools and test environments, and that it’s often a costly and time-consuming process.

Objective of Reliability Testing

1. To find the perpetual structure of repeating failures.
2. To find the number of failures occurring is the specific period of time.
3. To discover the main cause of failure.
4. To conduct performance testing of various modules of software product after fixing defects.
5. It builds confidence in the market, stakeholders and users by providing a dependable product that meets quality criteria and operates as expected.
6. Understanding the dependability characteristics and potential mechanisms of failure of the system helps companies plan and schedule maintenance actions more efficiently.
7. It evaluates whether a system or product can be used continuously without experiencing a major loss in dependability, performance or safety.
8. It confirms that in the absence of unexpected shutdown or degradation, the system or product maintains constant performance levels under typical operating settings.

Types of Reliability Testing

1. Feature Testing

Following three steps are involved in this testing:

• Each function in the software should be executed at least once.
• Interaction between two or more functions should be reduced.
• Each function should be properly executed.

2. Regression Testing

Regression testing is basically performed whenever any new functionality is added, old functionalities are removed or the bugs are fixed in an application to make sure with introduction of new functionality or with the fixing of previous bugs, no new bugs are introduced in the application.

3. Load Testing

Load testing is carried out to determine whether the application is supporting the required load without getting breakdown. It is performed to check the performance of the software under maximum work load.

4. Stress Testing

This type of testing involves subjecting the system to high levels of usage or load in order to identify performance bottlenecks or issues that can cause the system to fail.

5. Endurance Testing

This type of testing involves running the system continuously for an extended period of time in order to identify issues that may occur over time, such as memory leaks or other performance issues.
Recovery testing: This type of testing involves testing the system’s ability to recover from failures or crashes, and to return to normal operation.

6. Volume Testing

This type of testing involves testing the system’s ability to handle large amounts of data.
Soak testing: This type of testing is similar to endurance testing, but it focuses on the stability of the system under a normal, expected load over a long period of time.

7. Spike Testing

This type of testing involves subjecting the system to sudden, unexpected increases in load or usage in order to identify performance bottlenecks or issues that can cause the system to fail.

Measurement of Reliability Testing

Mean Time Between Failures (MTBF): Measurement of reliability testing is done in terms of mean time between failures (MTBF).

Mean Time To Failure (MTTF): The time between two consecutive failures is called as mean time to failure (MTTF).

Mean Time To Repair (MTTR): The time taken to fix the failures is known as mean time to repair (MTTR).

MTBF = MTTF + MTTR