MockMockWeb is a Heroku-ready Node.js-based Web application server which allows you to mock up a website in seconds. It allows you to instantly launch a website which sends an empty page (with status 200) to any request/URL and edit any page on the spot. You can also edit the layout shared throughout your website. It lets you build a mock (sometimes real) website in a request-driven interaction.
Flexmock is a mock/stub/spy library for Python. Its API is inspired by a Ruby library of the same name. However, it is not a goal of Python Flexmock to be a clone of the Ruby version. Instead, the focus is on providing full support for testing Python programs and making the creation of fake objects as unobtrusive as possible. Flexmock’s design focuses on simplicity and intuitiveness. This means that the API is as lean as possible, though a few convenient short-hand methods are provided to aid brevity and readability. Flexmock declarations are structured to read more like English sentences than API calls, and it is possible to chain them together in any order to achieve high degree of expressiveness in a single line of code.
ytest is a PHPUnit extension, based on the PHP extension "runkit", that allows you to replace static, private, and global functions with fakes, stubs, or mocks. This eases the automated testing of PHP applications that weren't written in a TDD fashion (i.e. test-first). It can also be helpful on projects where many methods are kept private, or projects that don't use OOP so much. ytest has already been used to "test after" (as opposed to "test first") some real-life commercial projects, and has proven useful. It needs PHP >= 5.2.