SimpleTest vs RSpec comparison of testing frameworks
What are the differences between SimpleTest and RSpec?

SimpleTest

https://github.com/simpletest/simpletest

RSpec

https://rspec.info
Programming language

PHP

Ruby

Category

Unit Testing, Web Testing

Unit Testing, Intergration Testing

General info

SimpleTest is a unit test and web test framework for PHP

It has JWebUnit style functionality and support for SSL, forms, frames, proxies and basic authentication

Domain Specific Language (DSL) testing solution for Ruby code

It focuses on empowering Test Driven Development (TDD). RSpec contains multiple smaller libraries, which may be independently used with other testing frameworks.
xUnit
Set of frameworks originating from SUnit (Smalltalk's testing framework). They share similar structure and functionality.

No

Yes

Yes, but it differs from more traiditional xUnit solutions. Its tests are written in a "Tests as Specification" manner. This means that the terminology used in RSpec is adjusted to a language more fitting for specification.
Client-side
Allows testing code execution on the client, such as a web browser

Yes

With SimpleTest common but fiddly PHP tasks, such as logging into a site, can be tested easily

Yes

RSpec is used to primarily test the behaviour of applications or individual components so it can test front-end behaviour as well - you can use capybara gem with RSpec for that.
Server-side
Allows testing the bahovior of a server-side code

Yes

Server-side behaviour can be tested by writing simple unit tests to test functionality and behaviour of single components.

Yes

You can test server-side behaviour with Rspec
Fixtures
Allows defining a fixed, specific states of data (fixtures) that are test-local. This ensures specific environment for a single test

Yes

It can import fixtures using a mixin like 'given()' method

Yes

RSpec does contain fixture methods
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

It allows grouping of fixtures

Yes

Group fixture methods are supported
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

Simpletest has support for generators

Yes

RSpec contains generators for example intergration_'test_name' which will save a spec inside the spec/requests folder
Licence
Licence type governing the use and redistribution of the software

GNU Lesser General Public License v2.1

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

It allows for one to build Mock objects.To create a mock version of a class we need to include the mock object library and run the generator. This will create a clone class which we use to create new instances(objects) in our test cases.

Yes

Available through rspec-mocks gem.
Grouping
Allows organizing tests in groups

Yes

There are several ways of grouping tests; one is to simply place multiple test cases into a single file, another is to mark any base test cases that should not be run as abstract, Simpletest gives you a couple of options

Yes

Allows declaring example groups and contexts.
Other
Other useful information about the testing framework