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

Windmill

https://pypi.org/project/windmill/

NUnit

https://nunit.org/
Programming language

Python

.NET

Category

UI Testing

Unit Testing

General info

Windmill is an Open Source Web UI testing framework for Python

Windmill is an Open Source AJAX Web UI testing framework that implements in-browser recording and playback, cross browser testing and test integration

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

Its main function is testing of 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

No

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

N/A

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.

N/A

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 third party libraries

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)

N/A

Yes

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

N/A

Yes

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