Testing software or applications aims to build a quality product. Functional testing and unit testing are the backbones of software testing.
Unit Testing : In its simplest form, unit testing entails testing individual components or units within the software. In this step, each unit of code is validated and checked to determine if it is performing as you expected it to.
Functional Testing : This type of software testing evaluates a system's functionality against the functional requirements. Each software component is first checked for its expected output, then tested twice to ensure that its output does not impact the rest of the system.
| Unit Testing |
Functional Testing |
| In this type of test, the smallest units or modules are tested individually. |
It verifies that an application performs as expected. |
| It is possible to find issues that crop up frequently in modules by running unit tests. |
A functional test identifies the issues preventing an application from performing correctly. This may include scenario-based issues as well. |
| There is no chance for the issue to escape. |
As the number of tests to run is always infinite, there is a higher chance of issues escaping. |
| In other words, it is a form of white-box testing. |
Essentially, it is black-box testing. |
| A unit test is fast and can help write clean code, but it cannot assure that the app will work as intended. It shows us where errors are in the code, though. |
A functional test takes time and effort but ensures the system will meet functional requirements. The test identifies any problems or defects in the functionality. |
