test(tests): added test suite

The test suite is extensive. Note that LLMs were used to aid in the development of the test suite. All LLM generated code was manually reviewed.

tests/sandbox/rayfem_sandbox.cpp

@@ -0,0 +1,25 @@
+#include <cmath>
+#include <print>
+
+#include "mfem.hpp"
+#include "libRayfem/io/serif.hpp"
+#include "libRayfem/mesh/converter.hpp"
+
+/** @brief Exercise the visualization dependency without opening a window or running a solve. */
+int main() {
+    auto mesh = mfem::Mesh::MakeCartesian2D(2, 2, mfem::Element::QUADRILATERAL, true, 1.0, 1.0);
+    mfem::H1_FECollection collection(2, 2);
+    mfem::FiniteElementSpace space(&mesh, &collection);
+    mfem::GridFunction field(&space);
+    mfem::FunctionCoefficient coefficient([](const mfem::Vector& x) { return x[0] + 2.0 * x[1]; });
+    field.ProjectCoefficient(coefficient);
+
+    const auto surface = RayFEM::BuildSurface(mesh, &field);
+    if (!RayFEM::SerifLoadingAvailable() || surface.values.empty() ||
+        std::abs(surface.min_value) > 1.0e-12 || std::abs(surface.max_value - 3.0) > 1.0e-12) {
+        std::println(stderr, "RayFEM could not evaluate the parent MFEM field or load SERiF archives.");
+        return 1;
+    }
+    std::println("RayFEM evaluated the MFEM field through serif_dep; SERiF archive support is available.");
+    return 0;
+}