Windmill vs go test/testing comparison of testing frameworks
What are the differences between Windmill and go test/testing?

Windmill

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

go test/testing

https://golang.org/pkg/testing/
Programming language

Python

Go

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

go test is an inbuilt tool/command for conducting automated tests in Golang while testing is the inbuilt testing library

Testing is the package that is shipped with go and combines with the go test command to provide a minimal but complete testing experience
xUnit
Set of frameworks originating from SUnit (Smalltalk's testing framework). They share similar structure and functionality.

No

No

However there are Plugins such as https://github.com/tebeka/go2xunitto convert the output of Go testing library into xUnit format
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

Yes it can be used effectively for front-end testing
Server-side
Allows testing the bahovior of a server-side code

No

Yes

Yes, it is used by developers for end-to-end testing so the back-end can be tested easily as well
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

Yes it's straightforward in that first when you run 'go test' for packages in the scope the test will be executed with its working directory set to the source directory of the package being tested. Second the 'go test' tool will ignore any directory in your $GOPATH that starts with the word 'testdata' , starts with a period or an underscore
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 can be done following a similar procedure as a single fixture
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

Yes

They are available by importing a package called 'gotests' (https://github.com/cweill/gotests)
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

By use of a third party library GoMock which intergrates well with the testing library
Grouping
Allows organizing tests in groups

N/A

Yes

The short answer is yes, by use of table tests which are a great way of performing multiple I/O tests on a function or behaviour with minimal code
Other
Other useful information about the testing framework