1. Functional Bugs

Functional bugs occur when an application or system does not behave as intended, failing to meet specified functional requirements.

Here’s a breakdown of common types:

1. Incorrect Calculations

- Errors in arithmetic operations, tax computations, or discount calculations.

- Example: A shopping cart totals items incorrectly.

2. Navigation Bugs

- Broken links or buttons that don’t lead to the correct page.

- Example: Clicking "Next" redirects to the wrong section.

3. Validation Errors

- Forms accepting invalid inputs or rejecting valid ones.

- Example: A date of birth field accepts future dates.

4. Workflow Issues

- Disruptions in multi-step processes or user flows.

- Example: A payment process doesn’t allow completion after the card is entered.

5. Missing Functionality

- Features explicitly stated in requirements are not present.

- Example: A search function is missing on a website.

6. Incorrect Output

- The application delivers results that are inconsistent with expected outputs.

- Example: Generating incorrect reports or analytics.

7. State Management Issues

- Problems with session handling or saving user progress.

- Example: A shopping cart empties unexpectedly when moving between pages.

8. Data Retrieval/Storage Defects

- Issues in fetching, displaying, or saving data.

- Example: A profile page fails to show all user details correctly.

9. Notifications and Alerts

- Failure in sending, receiving, or displaying messages.

- Example: Missing email confirmations or error pop-ups.

10. Localization Errors

- Functional issues related to language, time zones, or region-specific content.

- Example: The wrong currency is displayed for international users.

These bugs can undermine user trust and satisfaction if not resolved. Functional testing and rigorous quality assurance processes are crucial to catching and fixing these issues.