build(cmake): isolate test-only dependencies

tests/unit/core/version_test.cpp

@@ -0,0 +1,11 @@
+#include <gtest/gtest.h>
+
+#include <fesa/core/version.hpp>
+
+namespace {
+
+TEST(Version, ReportsPhaseOneSemanticVersion) {
+    EXPECT_EQ(fesa::version(), "0.1.0");
+}
+
+}  // namespace

tests/unit/dependencies/dependency_smoke_test.cpp

@@ -11,6 +11,8 @@
 
 namespace {
 
+static_assert(sizeof(MKL_INT) == 4, "FESA requires the oneMKL LP64 interface.");
+
 TEST(DependencySmoke, CallsOneMklVectorOperation) {
     constexpr std::array<double, 3> x{1.0, 2.0, 3.0};
     std::array<double, 3> y{4.0, 5.0, 6.0};