test: Add tests for policy

Author: FrozenLemonTee

tests/basic/test_policies.cpp

@@ -0,0 +1,33 @@
+#include <gtest/gtest.h>
+
+import mcpplibs.primitive;
+
+namespace {} // namespace
+
+using namespace mcpplibs::primitive;
+
+TEST(PolicyTraitsTest, BuiltinPoliciesHaveCategories) {
+  using namespace policy;
+
+  EXPECT_TRUE((policy::traits<policy::checked_value>::enabled));
+  EXPECT_EQ(policy::traits<policy::checked_value>::kind,
+            policy::category::value);
+
+  EXPECT_TRUE((policy::traits<policy::relaxed_type>::enabled));
+  EXPECT_EQ(policy::traits<policy::relaxed_type>::kind, policy::category::type);
+
+  EXPECT_TRUE((policy::traits<policy::throw_error>::enabled));
+  EXPECT_EQ(policy::traits<policy::throw_error>::kind, policy::category::error);
+
+  EXPECT_TRUE((policy::traits<policy::single_thread>::enabled));
+  EXPECT_EQ(policy::traits<policy::single_thread>::kind,
+            policy::category::concurrency);
+
+  EXPECT_TRUE((policy_type<policy::checked_value>));
+  EXPECT_FALSE((policy_type<int>));
+
+  EXPECT_TRUE((std::is_same_v<policy::default_policies::value,
+                              policy::unchecked_value>));
+}
+
+// Use the existing test runner main from other test translation unit.