Selenium vs NUnit comparison of testing frameworks
What are the differences between Selenium and NUnit?

Selenium

https://pypi.org/project/selenium/

NUnit

https://nunit.org/
Programming language

Python

.NET

Category

Web Automation

Unit Testing

General info

Selenium is an open source tool used to test web applications

Selenium is a powerful testing tool which can send standard Python commands to different browsers, despite variations in browser design. It also provides extensions to emulate user interaction with browsers, a distribution server for scaling browser allocation, and the infrastructure for implementations of the W3C WebDriver specification that lets you write interchangeable code for all major web browsers

NUnit is an open-source unit testing framework for Microsoft .NET.

NUnit was Initially ported from JUnit. Tests can be run from a console runner, within Visual Studio through a Test Adapter or through 3rd party runners. Tests can be run in parallel and has Strong support for data driven tests. Unit supports multiple platforms including .NET Core, Xamarin Mobile, Compact Framework and Silverlight.
xUnit
Set of frameworks originating from SUnit (Smalltalk's testing framework). They share similar structure and functionality.

No

Yes

Nunit is one of many programs in the xUnit family
Client-side
Allows testing code execution on the client, such as a web browser

Yes

It is primarily a browser automation tool which tests front-end components and functionality

Yes

You can test front-end components with NUnit since it is a Unit testing framework the application is isolated into diverse modules which are tested independently
Server-side
Allows testing the bahovior of a server-side code

Yes

It can perform Unit tests and can test various components and behaviours in the backend using a BDD or TDD approach

Yes

You can test back-end components with NUnit, it is a Unit testing framework hence the application is isolated into diverse modules which are tested independently
Fixtures
Allows defining a fixed, specific states of data (fixtures) that are test-local. This ensures specific environment for a single test

Yes

By writing your Selenium WebDriver tests in PyTest, this gives you access to Pytest's powerful fixture model

Yes

NUnit contains the fixture methods SetUp to initialize your test environment and TearDown method to destroy a test environment
Group fixtures
Allows defining a fixed, specific states of data for a group of tests (group-fixtures). This ensures specific environment for a given group of tests.

Yes

One can group fixtures if accessing Pytest's fixture model

Yes

Group fixtures are available in NUnit
Generators
Supports data generators for tests. Data generators generate input data for test. The test is then run for each input data produced in this way.

Yes

By using a library such as Faker or Fake-factory

N/A

Licence
Licence type governing the use and redistribution of the software

Apache License 2.0

MIT License

Mocks
Mocks are objects that simulate the behavior of real objects. Using mocks allows testing some part of the code in isolation (with other parts mocked when needed)

Yes

It includes support for mocking

Yes

You can create mock objects using the third party library moq
Grouping
Allows organizing tests in groups

Yes

By using the TestNG feature with which we can create groups and maintain them easily

Yes

You can group tests into suites with NUnit
Other
Other useful information about the testing framework