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

Windmill

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

Shoulda

https://github.com/thoughtbot/shoulda
Programming language

Python

Ruby

Category

UI 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

Meta gem containing Shoulda Context and Shoulda Matchers

Shoulda contains two other gems: Should Context and Shoulda Matchers. Should Context allows better naming and grouping of your tests. Shoulda Matchers provides a set of "matchers", i.e. methods that allow you to write much more concise assertions.
xUnit
Set of frameworks originating from SUnit (Smalltalk's testing framework). They share similar structure and functionality.

No

No

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

N/A

Server-side
Allows testing the bahovior of a server-side code

No

N/A

Fixtures
Allows defining a fixed, specific states of data (fixtures) that are test-local. This ensures specific environment for a single test

N/A

N/A

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

N/A

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

N/A

Grouping
Allows organizing tests in groups

N/A

Yes

Other
Other useful information about the testing framework

Shoulda Context is compatible with Minitest and Test::Unit. Shoulda Matchers is compatible with RSpec and Minitest.