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

Cucumber

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

Espec

https://github.com/antonmi/espec
Programming language

Ruby

Elixir

Category

Acceptance Testing

Unit 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.

BDD driven testing framework for Elixir

It is a testing framework written from scratch which is inspired by RSpec and the main idea is to close to its perfect DSL (Domain Specific Language)
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

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

Yes

Front-end components can be tested; there is also espec_phoenix for the Phoenix web framework
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

databases and server behaviour can be tested using Espec
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

N/A

Licence
Licence type governing the use and redistribution of the software

MIT License

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)

Yes

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

Yes

It has a Built-in mocking functionality on top of Erlang 'meck' library
Grouping
Allows organizing tests in groups

No

Yes

By use of context blocksand tags functions
Other
Other useful information about the testing framework