Update docs to include how to use lambdas within regular test cases?

[robamu]

Hello,

The feature of nesting multiple sections into each other is really useful. Sometimes, I'd prefer something like functions though, where I can share the same code (which might include CHECKs and REQUIREs) across multiple sections. Maybe I missed something in the documentation, but I have found C++ lambdas to be extremely useful for this, and I can't use regular function definitions inside the TEST_CASE scope.

For example consider something like this

#include <catch2/catch_test_macros.hpp>

TEST_CASE("Test", "[test]") {
    uint32_t answer = 42;
    uint32_t foo = 10;

    auto sharedTestCode = [&](bool changeAnswer) {
        if(changeAnswer) {
            answer = foo;
        }
        CHECK(foo == 10);
    };

    SECTION("Section 0") {
        sharedTestCode(false);
        CHECK(answer == 42);
    }

    SECTION("Section 1") {
        sharedTestCode(true);
        CHECK(answer == 10);
    }

}

Do you think this is something worth mentioning in the doucmentation? Maybe this is also a case where a test fixture would be a better option in that case, but using lambdas has worked well enough for me to use the recommended way to use Catch2.

Kind Regards
Robin Müller

[nandanvasudevan]

I do this all the time, isn't it just C++?

[robamu]

One could argue it's just C++, but it is usually possible to do work in C++ without lambdas entirely, especially when coming from a C background. In the context of Catch2 I have not found a way to have something similar to functions inside a Catch2 test case without lambdas. That's why I though it might be a nice idea to mention/include it in the docs.