# What Is Functional Testing?

## Definition

Functional testing verifies whether a system behaves according to a specified requirement, such as saving a setting or returning the expected search result.

## Why it matters

The assertion is the core of the test. Completing actions without an explicit expected result may prove only that the actions did not throw an error.

## How teams handle it today

Teams express the starting state, user action and expected outcome, then choose the right test layer. They update the test when the intended behavior changes.

## How Zerocheck approaches it

Zerocheck drafts browser tests from the actions and expected outcome you provide. Each saved YAML test ends with a Verify step. Run details preserve the exact steps and their observed results for review.

Related terms: [E2E Testing](https://tryzerocheck.com/glossary/e2e-testing/), [Regression Testing](https://tryzerocheck.com/glossary/regression-testing/), [Test Automation](https://tryzerocheck.com/glossary/test-automation/)


---
Canonical: https://tryzerocheck.com/glossary/functional-testing/
Updated: 2026-09-14