완성된 HHT trial의 constraint 자료 중복 평가 제거

tests/unit/math/dense_blas_internal_test.cpp

@@ -11,6 +11,39 @@
 namespace fesa::dense_blas_internal {
 namespace {
 
+TEST(DenseBlasInternal, PolicyQueryPreservesDefaultPositiveAndNestedTls) {
+  const int previous = mkl_set_num_threads_local(0);
+  struct Restore {
+    int previous;
+    ~Restore() { static_cast<void>(mkl_set_num_threads_local(previous)); }
+  } restore{previous};
+  const int global = mkl_get_max_threads();
+  const int domain = mkl_domain_get_max_threads(MKL_DOMAIN_BLAS);
+  const int dynamic = mkl_get_dynamic();
+  for (int repeat = 0; repeat < 2; ++repeat) {
+    const auto policy = ReadScopedLocalDensePolicy();
+    EXPECT_EQ(policy.blas_max_threads, 1);
+    EXPECT_EQ(policy.dynamic, dynamic);
+    EXPECT_EQ(mkl_set_num_threads_local(0), 0);
+    EXPECT_EQ(mkl_get_max_threads(), global);
+    EXPECT_EQ(mkl_domain_get_max_threads(MKL_DOMAIN_BLAS), domain);
+    EXPECT_EQ(mkl_get_dynamic(), dynamic);
+  }
+  static_cast<void>(mkl_set_num_threads_local(2));
+  EXPECT_EQ(ReadScopedLocalDensePolicy().blas_max_threads, 2);
+  EXPECT_EQ(mkl_set_num_threads_local(2), 2);
+  static_cast<void>(mkl_set_num_threads_local(0));
+  try {
+    const ScopedLocalDenseThreads outer{};
+    EXPECT_EQ(ReadScopedLocalDensePolicy().blas_max_threads, 1);
+    EXPECT_EQ(mkl_set_num_threads_local(1), 1);
+    throw std::runtime_error{"policy-query-unwind"};
+  } catch (const std::runtime_error&) {
+  }
+  EXPECT_EQ(mkl_set_num_threads_local(0), 0);
+  EXPECT_EQ(mkl_get_dynamic(), dynamic);
+}
+
 TEST(DenseBlasInternal,
      OuterProductUsesRectangularStorageAndPreservesRejection) {
   const std::array<double, 2U> left{2.0, -3.0};