feat(solver-bootstrap): step 3 — core-ids-and-diagnostics

tests/unit/core/entity_id_test.cpp

@@ -0,0 +1,36 @@
+#include <cstdint>
+#include <stdexcept>
+#include <type_traits>
+
+#include <gtest/gtest.h>
+
+#include <fesa/core/entity_id.hpp>
+
+namespace {
+
+struct NodeTag;
+struct ElementTag;
+
+using NodeId = fesa::EntityId<NodeTag>;
+using ElementId = fesa::EntityId<ElementTag>;
+
+static_assert(std::is_constructible_v<NodeId, std::int64_t>);
+static_assert(!std::is_convertible_v<std::int64_t, NodeId>);
+static_assert(!std::is_convertible_v<NodeId, ElementId>);
+
+TEST(EntityId, PreservesValueAndSupportsTypedOrdering) {
+    constexpr NodeId first{7};
+    constexpr NodeId second{11};
+
+    static_assert(first.value() == 7);
+    static_assert(first < second);
+
+    EXPECT_EQ(first.value(), 7);
+    EXPECT_LT(first, second);
+}
+
+TEST(EntityId, RejectsNegativeValues) {
+    EXPECT_THROW((NodeId{-1}), std::invalid_argument);
+}
+
+}  // namespace