Functional testing is a black-box testing approach that validates whether a software application performs according to its functional requirements. It focuses on what the system does rather than how it does it, ensuring each feature works as intended without inspecting the source code.

Key focus areas include:

• User Interface (UI) navigation and usability.

• APIs and data handling.

• Database operations.

• Security and access control.

• Error handling and messaging.

Typical process:

1. Identify test inputs – Determine core features and scenarios, including valid/invalid data.

2. Compute expected outcomes – Define expected results from requirements.

3. Execute test cases – Run tests manually or via automation tools like Selenium, QTP/UFT, or Testsigma.

4. Compare actual vs expected results – Confirm correctness or log defects.

Common types:

• Unit Testing – Validates individual modules.

• Integration Testing – Checks interactions between modules.

• System Testing – Verifies the complete integrated system.

• Regression Testing – Ensures changes don’t break existing features.

• Smoke/Sanity Testing – Quick checks for build stability.

• User Acceptance Testing (UAT) – End-user validation before release.

• End-to-End Testing – Validates complete workflows.