converting from boost to catch test framework

[conradsnicta]

The (temporary) tests_catch/ directory contains the converted tests from boost to catch. This is currently a work in progress.

I've converted about a third of the tests and came up with the following conversion rules. I'm not sure whether these are completely correct, so it would be useful to check these.

BOOST_AUTO_TEST_SUITE(blah) -> delete, but "blah" is used as the second argument to all instances of TEST_CASE() within a given file

BOOST_AUTO_TEST_SUITE_END() -> delete

BOOST_AUTO_TEST_CASE(testname) -> TEST_CASE("testname", "[blah]")
following the examples given in the Catch2 tutorial

BOOST_REQUIRE_SMALL(x, 0.015) -> REQUIRE(x == Approx(0.0).margin(0.015))
as per the docs for Catch2 assertion macros; not sure whether this is the best or even the correct approach

BOOST_REQUIRE_CLOSE(x, 1.23, 0.15) -> REQUIRE(result == Approx(1.23).epsilon(0.0015))
Boost uses the "0.15" to express 0.15%. I'm not certain on the Catch2 equivalent expression. I've followed the example in the docs for assertion macros, which uses .epsilon(0.01) to express a 1% difference. The Catch2 docs appear unclear on the exact meaning of .epsilon(val): "epsilon serves to set the coefficient by which a result can differ from Approx's value before it is rejected." Coefficient of what?

BOOST_REQUIRE_EQUAL(i, 123) -> REQUIRE(i == 123)
BOOST_REQUIRE_GT(x, 0.05) -> REQUIRE(x > 0.05)
BOOST_REQUIRE_GE(x, 0.05) -> REQUIRE(x >= 0.05)
BOOST_REQUIRE_LT(x, 0.05) -> REQUIRE(x < 0.05)
BOOST_REQUIRE_LE(x, 0.05) -> REQUIRE(x <= 0.05)

[zoq]

BOOST_REQUIRE_SMALL(x, 0.015) -> REQUIRE(x == Approx(0.0).margin(0.015))

I guess you could also write REQUIRE(std::abs(x) <= 0.015), but I think it makes sense to check against the plain output (x ).

The rest looks reasonable to me, as I understand the doc REQUIRE(result == Approx(1.23).epsilon(0.0015)) is the equivalent of BOOST_REQUIRE_CLOSE(x, 1.23, 0.15), worked on a couple of examples.

[conradsnicta]

The REQUIRE(std::abs(x) <= 0.015) form is certainly more compact. However, std::abs() only works for signed types. Using size_t or arma::uword wouldn't work. From what I have seen in the current tests, not all of the values that are checked are floats. Probably a minor issue, but it would be easier not to worry about these special cases by simply being consistent with the use of the REQUIRE(x == Approx(0.0).margin(0.015)) form.