Catch: A modern, C++-native, header-only, framework for unit tests | Hacker News Reader

Catch: A modern, C++-native, header-only, framework for unit tests

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95 pointstbrock30 comments

To be honest, I prefer bandit[1], it uses lambdas instead of macros which I consider more modern and it has a nice syntax to it. Anyone interested in catch should also check out bandit.

[1] http://banditcpp.org/index.html

I found the Bandit examples rather disorienting. Can anyone explain what the "[&](){" business means?

That's the syntax for describing a lambda function.

CPP reference has a nice overview of it: http://en.cppreference.com/w/cpp/language/lambda

One advantage of Catch is that you can use native C++ expressions in your assertions, so instead of

  AssertThat(guitar->sound(), Equals(sounds::clean));

you can write

  CHECK(guitar->sound() == sounds::clean);

And you'll still get sensible output when it fails, showing the expression and the result of guitar->sound().

This isn't so much an advantage as a preference.

See https://github.com/joakimkarlsson/snowhouse#assertions

I don't really see the advantage of Catch over http://unittest-cpp.sourceforge.net/

UnitTest++ was written by Noel Llopis, is small, tasteful, fast, and supports fixtures (and nested fixtures) via structs and struct inheritance.

Honest question: Why would I use Catch instead?

I'm in the same boat (having used UnitTest++ for years) and I wonder the same, though I do see some points already:

- adding a custom main() to unittest++ was pretty messy

- unittest++ is not single-header, meaning you have to recompile all flavours everytime you switch toolsets

- that nested sections stuff looks good and readable, so even though it might be doable with unittest++, this really attracts me more

That being said, I would like to hear from the author or anyone else who can compare them. But likely I'm going to use this for the next project just to check it out.

I'm a big fan of UnitTest++, but one thing that would tempt me about Catch is the single header file.

I use Catch over UnitTest++ because I found it first and it was dead simple to get started with.

We don't do unit-testing as part of our official development process where I work, so I was looking for something that I could quickly try out and get started with in my spare moments. I read about several frameworks and Catch seemed to fit the bill best.

Looking over the UnitTest++ web site just now it appears to be nearly as easy as Catch, so if I had found it first I probably would have given it a try.

For those not currently doing any unit testing who want to get a feel for what it is all about, I highly recommend Catch as a "my first unit testing framework."

This looks hella good, I particularly am intrigued by the nested setup/teardown system. The natural assert syntax is interesting, too, amazing what macros can accomplish.

Appropriately, the first question that came to mind was, "what's the catch?" :)

Yup. I found it interesting after a co-worker pointed it out to me because it looks and works kind of like RSpec. We are currently considering using it for a new project and it seems mature enough to give it a go.

I'm currently toying with writing a JSONReporter so we can use that as an additional test result output format and I agree, so far it seems to be a really well done project.

FWIW I've been using Catch for a few years now, and I find it mature enough for real world usage.

Good to know, thanks!

The biggest turnoff to me is the sheer quantity of code (regardless of the fact that it can all be crammed into a single header file). It seems much more difficult to fix a bug in it than in something like UnitTest++.

That said, inline setup/teardown and parsing expressions in asserts seem like such natural ideas, I can't believe I haven't run across frameworks doing them before. I guess the shadow of JUnit is extremely long.

The macro trick is at https://github.com/philsquared/Catch/blob/785db43bb2cd64bfe7...: planting the tested expression to the right of an operator ->*, which is overloadable and allows for changing the type of the left hand side in the comparison. The rest is a "simple matter of programming". Clever but probably a bit cute - errors would look weird if the expression isn't set up as expected.

Also uses template to overload operator ->*

https://github.com/philsquared/Catch/blob/785db43bb2cd64bfe7...

It looks like a nice test framework, but it doesn't appear to help at all with the really hard problems you face with testing C++ -- isolating the unit under test for separate compilation, and the development and inclusion of mocks/stubs.

Anyone know of a really good (preferably simple and pragmatic) C++ mocking/stubbing framework to go with this?

Why do you want to compile the unit test separately?

Because that's what makes it a unit test -- you only want the unit, the tests and any stubs/mocks in the executable. Anything more and you have an integration test on your hands.

Pulling a single unit out of a legacy codebase can be difficult, especially when you don't want to actually move, copy, or modify the source-files; stubbing out the dependencies and writing mock objects to verify your expectations of what the code should be doing are also very time-consuming.

Those are the hard parts of unit testing C++, and I wonder if anyone has found a good way of doing it (with a framework, or just a technique).

Not to steal your thunder, but TUT (Templated Unit Tests) does this as well, and I've found it works very nicely even in embedded and cross-platform:

https://mrzechonek.github.io/tut-framework/

It's lightweight, easy to setup for separated tests or built in tests, and simple to use. Doesn't add anything to help with mocking, but you can do that yourself.

EDIT: To followup, I created a C++ template that leverages TUT and binfmtc that I could use to rapidly iterate with. I used it for working out solutions to problems in "Thinking in C++"; it's posted at http://hardcorehackers.com/~npsimons/Template.hh

I really like the look of the "Sections" for managing setup/teardown of tests. I'm envious and next time I'm hacking on our in-house C# test framework I'm going to try very hard to implement them! Neat!

Great work. I love the fact that this encourages writing tests that are readable/documenting.

Definitely gonna give this a try.

Any recommended test runner to go with it?

There's a test runner included as a macro that defines main

A coworker of mine is working on something similar: https://github.com/Kosta-Github/cute

This looks really good. Do you plan to include BeforeEach and AfterEach? I'll try this out and maybe move my projects to this.

I started working on something similar[1] a few days ago just as a proof of concept.

[1] https://github.com/cEhlen/CUT/blob/master/example.cpp

A similar thing I knocked up a few years ago. Lacking in features and, well, most things - except it does have a pretty Qt based runner: http://www.rikkus.info/cplusplus-unit-testing-framework

Sorry for the off-topicness but I have to say...

I loved the project logo

I'm not a C++ programmer but this looks really neat and tidy. How does it work?

Any sufficiently advanced C++ template code is indistinguishable magic.

This looks very intriguing. Right now I am using Google Test for my projects, but a single header file for creating tests is awesome :-)

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