Catch/docs/why-catch.md

Why do we need yet another C++ test framework?

Good question. For C++ there are quite a number of established frameworks, including (but not limited to), CppUnit, Google Test, Boost.Test, Aeryn, Cute, Fructose and many, many more. Even for Objective-C there are a few, including OCUnit - which now comes bundled with XCode.

So what does Catch bring to the party that differentiates it from these? Apart from a Catchy name, of course.

Key Features

• Really easy to get started. Just download catch.hpp, #include it and you're away.
• No external dependencies. As long as you can compile C++98 and have a C++ standard library available.
• Write test cases as, self-registering, functions or methods.
• Divide test cases into sections, each of which is run in isolation (eliminates the need for fixtures!)
• Use BDD-style GIVEN-WHEN-THEN in place of test cases and sections.
• Only one core assertion macro for comparisons. Standard C/C++ operators are used for the comparison - yet the full expression is decomposed and lhs and rhs values are logged.

Other core features

• Tests are named using free-form strings - no more couching names in legal identifiers.
• Tests can be tagged for easily running ad-hoc groups of tests.
• Failures can (optionally) break into the debugger on Windows and Mac.
• Output is through modular reporter objects. Basic textual and XML reporters are included. Custom reporters can easily be added.
• JUnit xml output is supported for integration with third-party tools, such as CI servers.
• A default main() function is provided (in a header), but you can supply your own for complete control (e.g. integration into your own test runner GUI).
• A command line parser is provided and can still be used if you choose to provided your own main() function.
• Catch can test itself.
• Alternative assertion macro(s) report failures but don't abort the test case
• Floating point tolerance comparisons are built in using an expressive Approx() syntax.
• Internal and friendly macros are isolated so name clashes can be managed
• Support for Matchers (early stages)

Objective-C-specific features

• Automatically detects if you are using it from an Objective-C project
• Works with and without ARC with no additional configuration
• Implement test fixtures using Obj-C classes too (like OCUnit)
• Additional built in matchers that work with Obj-C types (e.g. string matchers)

See the tutorial to get more of a taste of using CATCH in practice

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