Difference between Errors, Defects and Failures in Software Testing

During the testing process, a software tester might come across several terms like errors, defects, failures, bugs, mistakes, and errors.

Let us understand the difference between Errors, Defects, Failures, Mistake, Fault and Bug.

Software Testers and quality analysts use these terms (error, mistakes, faults, bugs, failures, and defects) interchangeably. However, they signify and represent different aspects of the software.

These terms are the built-in part of the software testing lifecycle and you need to understand these terms clearly to validate the quality, effectiveness, and functionality of the software.

These terms have individual quality and are entirely different from one another.

The characteristics of occurrence and resolution of error, mistakes, faults, bugs, failures, and defects are different.

Let us go through each of these terms and understand the differences in detail:

What are Error and Mistake?

During the process of software testing, the team of testers has to face the most basic errors, and these are the mistakes made by the software developer or programmer while developing the code or design of the software.

Errors are the difference which we get from the results expected by the team, and errors further change the functionality of the software.

What are the reasons for error and mistakes?

The reasons for these mistakes and errors are the misunderstanding of requirements by the software developer.

Let us have a look at some other reasons for errors and mistakes in the software:

  • Mistakes made during code development in the program
  • Errors and mistakes may happen because of wrong coding logic, looping and syntax errors
  • Difference between actual and expected results – Misunderstanding of requirements by the developer

How to prevent Errors and Mistakes?

  • Implement a good code review process; reviews help to find the issues upfront and improve the quality of the software
  • Identify the issues and prepare a proper plan to rectify those issues
  • Verify the fixes after code deployment and confirm their quality and accuracy

What is Fault?

The fault is another discrepancy which is found by the tester during the process of software testing.

Unlike errors, the reason for a fault to occur is not because of some differences between the actual and expected result, but it is because of an error in software.

What are the reasons for faults?

Faults in software can occur because of various reasons, some of them are:

  • Discrepancies or issues in the software code because of which failure happens in the software
  • Incorrect process or steps followed which using the software
  • An inconsistency which makes the software act incorrectly and not as per the
    stated requirements

How to prevent Faults?

  • Proper code analysis implementation
  • Define proper Peer review process before code check-in

What is a failure?

When software is not able to perform as required and is presenting results that are not as per expected results, then it is termed as a failure.

These failures are incorrect external behavior which leads to software behaviour that is not in compliance with the specifications.

What are the reasons for Failures?

Failures occur when a defect present in the software is executed by the team, which forces to produce unpredicted results and function inappropriately.

Other reasons that may lead to the failure of the software are:

  1. Human errors and mistakes made while using the software and providing wrong or incomplete inputs.
  2. Users – Failures may also occur in the software or application if the user or client tries to perform operations that are disabled for that particular user or role
  3. Application Usage – Failures might also arise due to errors in the way application is being used.

How to prevent Failures?

  • First, identify and analyze errors and issues
  • Try to adopt effective preventive techniques
  • Perform re-testing and negative scenario testing
  • Verify and validate specifications and requirements thoroughly during all phases of development

What is a Defect?

Defect means when the actual result of the software differs from the one expected and predicted by the testers while testing the software.

Defects therefore are, defined as any difference encountered from the specifications mentioned in the product functional specification document by the client of the project.

These are the differences and issues in the software or application, found during the process of testing, that impact the functionality of the software and application.

What are the reasons for Defects?

Defects in the software can obstruct the functionality as well as the performance of the software application.

Hence, it is crucial for us to know the different reasons that cause defects in the software application.

Some of the other reasons for defects in software are:

  • The error made by the developer in code or incorrect coding logic causes software to perform inaccurately.
  • Any misunderstanding of requirements by developers can lead to defects
  • Updates to requirements in later phases of development lead to defects in the software or application
  • Setting up wrong and incorrect data for the software application

How to prevent Defects?

  • Implement a proper peer review process
  • Code reviews should be done on a regular basis to assess code quality and accuracy
  • Define and use effective software development methodologies
  • Adopt efficient programming techniques.
Preksha Rastogi

About Preksha Rastogi

Preksha is a freelance writer and has been writing tutorials and articles since 2015. Her areas of interest are Java, Testing, C and C++. Preksha has completed BCA and MCA from JIMS, New Delhi, India.

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