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Defect Management

  • In ISTQB, Defect Management refers to the process of identifying, documenting, prioritizing, resolving, and verifying defects found during the software development lifecycle. The aim of defect management is to ensure that defects are effectively tracked, managed, and resolved to improve the overall quality of the software. It also helps in providing insights into the software’s health and development process.

Defect​

  • A defect (Also known as a bug, fault, or issue) is any deviation between the expected and actual behavior of the software.

  • Defects can be identified during any phase of the software lifecycle but are most commonly found during testing.

  • A flaw or error in the software that causes it to produce incorrect or unexpected results, or behave in unintended ways.

Defect Types​

  • Functional Defects: Issues where the functionality does not meet the specified requirements.

  • Performance Defects: Problems related to the speed, responsiveness, or stability of the system.

  • Usability Defects: Issues that affect the user experience, such as confusing UI elements or poor navigation.

  • Security Defects: Vulnerabilities or weaknesses that could be exploited to compromise the system.

  • Compatibility Defects: Issues that occur when the software does not work properly across different environments. ie: Browsers, OS, and Hardware.

Defect Life Cycle​

  • The Defect Life Cycle (or Bug Life Cycle) describes the various stages a defect passes through from its discovery to its resolution and closure.

Key Stages

  • New: The defect has been identified and logged by a tester.

  • Assigned: The defect is assigned to a developer or team responsible for fixing it.

  • In Progress: The defect is being worked on by the developer.

  • Fixed: The defect has been resolved by the developer.

  • Retested: The tester retests the defect to verify the fix.

  • Verified: The defect has been successfully resolved and verified by the tester.

  • Closed: The defect is closed if the issue no longer exists.

  • Reopened: If the defect is still present after the fix, it is reopened and the process begins again.

Defect Statuses​

  • New: A newly identified defect that has not yet been assigned.

  • Open: A defect that is being analyzed or worked on.

  • Deferred: A defect whose resolution is postponed due to project priorities or other reasons.

  • Duplicate: A defect that has already been reported and logged.

  • Rejected: A defect that is not considered valid, such as an invalid issue or a misunderstanding of the requirement.

Defect Severity​

  • Defect Severity refers to the impact a defect has on the functionality or operation of the system. It is typically assigned by the tester and helps in understanding how critical the defect is to the application.

Severity Levels

  • Critical: The defect causes a complete failure of the software or a major feature, and there is no workaround. The system may be unusable.

  • Major: The defect affects significant functionality, but the system is still usable with some workarounds.

  • Minor: The defect impacts less critical functionality or causes cosmetic issues, but it does not significantly affect system operation.

  • Trivial: The defect has minimal impact on functionality, such as a minor UI defect or text issue.

Defect Priority​

  • Defect Priority refers to the urgency with which a defect should be fixed. It helps developers and project managers decide the order in which defects should be addressed. Priority is typically determined by project stakeholders (testers, developers, product owners).

Priority Levels

  • High: The defect needs to be fixed immediately as it is blocking further testing or has a major business impact.

  • Medium: The defect should be fixed soon, but it is not as urgent as high-priority defects.

  • Low: The defect can be fixed later or during a subsequent release, as it does not significantly impact the system.

Defect Density​

  • Defect Density is a metric that measures the number of defects per unit size of software, such as per thousand lines of code (KLOC) or per function point. It provides insight into the quality of the code and helps identify areas of the system that may need additional testing or review.

  • Defect Density formula helps compare the quality of different modules or releases. A high defect density indicates poor code quality or inadequate testing coverage.

    • Formula: Defect Density = Total Defects / Size of the Software (KLOC or Function Points)

Defect Report​

  • A Defect Report is a document that contains detailed information about a defect, enabling developers to analyze and fix the issue. A well-structured defect report is crucial for efficient defect management.

Key Components

  • Defect ID: A unique identifier for the defect.

  • Summary: A short description of the defect.

  • Description: A detailed explanation of the defect, including the steps to reproduce the issue, expected behavior, and actual behavior.

  • Severity and Priority: Indicates how critical the defect is and how urgently it should be fixed.

  • Environment: Information about the environment in which the defect occurred. ie: Operating System, Browser, and Device.

  • Attachments: Screenshots, logs, or other relevant files to help the developer understand the issue.

  • Status: The current status of the defect. ie: New, In Progress, and Fixed.

  • Assigned To: The person or team responsible for fixing the defect.

Defect Tracking System (DTS)​

  • A Defect Tracking System is a tool or software used to manage and track defects throughout their lifecycle. It facilitates communication between testers, developers, and managers, and ensures that defects are properly logged, prioritized, and resolved.

Common Defect Tracking Tools​

  • Jira: A widely-used issue tracking and project management tool.

  • Bugzilla: An open-source bug tracking system used by many software teams.

  • Mantis: A web-based bug tracking system.

  • Redmine: An open-source project management and issue-tracking tool.

Features of DTS​

  • Defect Logging: The ability to create and log new defects.

  • Workflow Management: Allows tracking the defect status through various stages.

  • Reporting and Analytics: Provides reports on defect metrics, such as open defects, defect density, and defect resolution rates.

  • Collaboration: Enables team members to comment on and discuss defects.

Defect Metrics​

  • Defect metrics provide quantitative measures to assess the effectiveness of defect management and the overall quality of the product. They help in identifying trends, areas for improvement, and the stability of the software.

Key Metrics

  • Defect Arrival Rate: The number of defects identified per unit of time. ie: Per Week or Per Release. It helps in identifying peaks in defect discovery and understanding the stability of the software.

  • Defect Fix Rate: The number of defects fixed per unit of time. A higher fix rate suggests that defects are being resolved quickly.

  • Defect Closure Rate: The rate at which defects are closed after verification.

  • Mean Time to Repair (MTTR): The average time taken to fix a defect from the time it is logged until it is resolved.

  • Reopen Rate: The percentage of defects that are reopened after being closed due to incomplete or incorrect fixes.

  • Defect Age: The amount of time a defect remains unresolved. A high defect age indicates delays in fixing defects.

Defect Prevention​

  • Defect prevention focuses on identifying the root cause of defects and taking actions to prevent similar defects from occurring in the future. This can be done through process improvements, better test coverage, or changes in development practices.

Key Concepts

  • Root Cause Analysis (RCA): Identifying the underlying causes of defects to prevent their recurrence. RCA helps in improving processes and preventing future defects.

  • Preventive Actions: Implementing changes to avoid defects, such as improved code reviews, better testing strategies, or enhanced development practices.

Defect Leakage​

  • Defect Leakage refers to defects that escape detection during a testing phase and are found later, often in production or by the customer. Defect leakage is a key quality indicator that reflects the effectiveness of the testing process.

Key Concepts

  • Leakage Rate: The percentage of defects found after testing is completed, typically in production. A high leakage rate indicates inadequate testing.

Module Review​

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