¿runvs?

How to test?

The test is now plain simple to write: Provide a function that returns a nullpointer and expect the constructor to throw in that case. TEST_CASE("Create SoundContext which cannot allocate ALDevice throws", "[SoundContext]") { SoundContext::DeviceFactoryT factory = []() { return std::unique_ptr (nullptr); }; REQUIRE_THROWS(SoundContext { factory }); }

What is spline interpolation?

Let's start from linear interpolation between a set of points. All that is needed for linear interpolation, are the positions (x,y) of the points. Spline interpolation takes this idea one step further. Each point now includes a slope k in addition to the x and y values. This allows not only to fit a linear function (aka a straight line) between the points, but a polynomial of order two.

How to set the k values (slope)?

There is still one piece of information missing: How to get the derivatives (k). There is, as usual, no one fits it all way to do it. The simplest way to handle this, is to set all k values to 0. This means, that all points given are extremal values (or saddle points). This means there are no overshoots.