Cucumber vs Lettuce comparison of testing frameworks
What are the differences between Cucumber and Lettuce?

Cucumber

https://github.com/cucumber/cucumber-ruby

Lettuce

https://pypi.org/project/lettuce/
Programming language

Ruby

Python

Category

Acceptance Testing

Unit Testing, Acceptance Testing

General info

An automation tool for Behavior-Driven Development

The specifications are written in plain texts, which allows them to be easily understandable for all stakeholders. Cucumber Framework also supports languages beyond Ruby e.g. Java, JavaScript and Scala.

Lettuce is a BDD testing tool for Python

Lettuce is a testing tool for Python which is inspired by Ruby's Cucumber that supports Gherkin. It can execute plain-text functional descriptions as automated tests for Python projects just like Cucumber does for Ruby
xUnit
Set of frameworks originating from SUnit (Smalltalk's testing framework). They share similar structure and functionality.

No

No

However It can generate xml results for behaviour tests xUnit style
Client-side
Allows testing code execution on the client, such as a web browser

Yes

You can test the front-end part like the GUI using cucumber and selenium, they integrate well to test your front-end.

Yes

By integrating Lettuce with Selenium’s Python bindings, you have a robust framework for testing Django applications. It can test front-end behaviour
Server-side
Allows testing the bahovior of a server-side code

Yes

You can test back-end components such as APIs using rest & soap clients, and databases using whatever client libraries were provided by the libraries that existed in those stacks

Yes

Lettuce can test various server and database behaviours and interactions
Fixtures
Allows defining a fixed, specific states of data (fixtures) that are test-local. This ensures specific environment for a single test

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.

Yes

Using the cucumber extension aruba you can create fixures in two steps: 1.Create a fixtures-directory; 2.Create fixture files in this directory

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

You can group your fixtures inside your fixtures directories

Yes

By using a third party library
Licence
Licence type governing the use and redistribution of the software

MIT License

Unknown

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

By using all of RSpec’s supported mocking frameworks (RSpec, Mocha, RR, Flexmock)

By adding the lettuce-tools library one has access to the Mock module to implement a configurable http REST mock.
Grouping
Allows organizing tests in groups

No

Yes

It allows grouping of tests
Other
Other useful information about the testing framework