Test’em vs Lettuce comparison of testing frameworks
What are the differences between Test’em and Lettuce?

Test’em

https://github.com/testem/testem

Lettuce

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

JavaScript

Python

Category

Unit Testing

Unit Testing, Acceptance Testing

General info

A Unit testing test runner for JavaScript

Test'em is framework agnostic and has support for Jasmine, Qunit, Mocha and others through custom test framework adapters. It canalso run tests on all major browsers as well as Node and Phantomjs

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.

It has an xUnit reporter

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

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

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.

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

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)

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

Yes

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