From 17753316f82622b6c93055f6c5e907df0dd6731d Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Tue, 6 Jan 2026 15:34:51 -0500
Subject: [PATCH] xo-arena: DArena unit test

---
 CMakeLists.txt              |  2 +-
 include/xo/arena/DArena.hpp |  3 ++
 src/arena/DArena.cpp        | 16 ++++++++++
 utest/CMakeLists.txt        | 23 ++++++++++++++
 utest/DArena.test.cpp       | 61 +++++++++++++++++++++++++++++++++++++
 utest/arena_utest_main.cpp  |  6 ++++
 6 files changed, 110 insertions(+), 1 deletion(-)
 create mode 100644 utest/CMakeLists.txt
 create mode 100644 utest/DArena.test.cpp
 create mode 100644 utest/arena_utest_main.cpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 24d544e..36fbfcb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,7 +21,7 @@ add_definitions(${PROJECT_CXX_FLAGS})
 # output targets
 
 add_subdirectory(src/arena)
-#add_subdirectory(utest)
+add_subdirectory(utest)
 
 # ----------------------------------------------------------------
 # cmake export
diff --git a/include/xo/arena/DArena.hpp b/include/xo/arena/DArena.hpp
index f9c2e3c..3ad10db 100644
--- a/include/xo/arena/DArena.hpp
+++ b/include/xo/arena/DArena.hpp
@@ -219,6 +219,9 @@ namespace xo {
              **/
             void clear() noexcept;
 
+            /** swap contents (including configuration) with another arena **/
+            void swap(DArena & other) noexcept;
+
             ///@}
 
             /** @defgroup mm-arena-instance-vars **/
diff --git a/src/arena/DArena.cpp b/src/arena/DArena.cpp
index 5c0e364..ecd698a 100644
--- a/src/arena/DArena.cpp
+++ b/src/arena/DArena.cpp
@@ -616,6 +616,22 @@ namespace xo {
             this->free_ = lo_;
             this->establish_initial_guard();
         }
+
+        void
+        DArena::swap(DArena & other) noexcept
+        {
+            std::swap(config_, other.config_);
+            std::swap(page_z_, other.page_z_);
+            std::swap(arena_align_z_, other.arena_align_z_);
+            std::swap(lo_, other.lo_);
+            std::swap(committed_z_, other.committed_z_);
+            std::swap(last_header_, other.last_header_);
+            std::swap(free_, other.free_);
+            std::swap(limit_, other.limit_);
+            std::swap(hi_, other.hi_);
+            std::swap(error_count_, other.error_count_);
+            std::swap(last_error_, other.last_error_);
+        }
     }
 } /*namespace xo*/
 
diff --git a/utest/CMakeLists.txt b/utest/CMakeLists.txt
new file mode 100644
index 0000000..34bf3ca
--- /dev/null
+++ b/utest/CMakeLists.txt
@@ -0,0 +1,23 @@
+# xo-alloc2/utest/CMakeLists.txt
+#
+
+set(UTEST_EXE utest.arena)
+set(UTEST_SRCS
+    arena_utest_main.cpp
+#    objectmodel.test.cpp
+    DArena.test.cpp
+#    DArenaIterator.test.cpp
+#    Collector.test.cpp
+#    DX1CollectorIterator.test.cpp
+#    random_allocs.cpp
+)
+
+if (ENABLE_TESTING)
+    xo_add_utest_executable(${UTEST_EXE} ${UTEST_SRCS})
+    xo_self_dependency(${UTEST_EXE} xo_arena)
+#    xo_headeronly_dependency(${UTEST_EXE} randomgen)
+#    xo_headeronly_dependency(${UTEST_EXE} indentlog)
+    xo_external_target_dependency(${UTEST_EXE} Catch2 Catch2::Catch2)
+endif()
+
+# end CMakeLists.txt
diff --git a/utest/DArena.test.cpp b/utest/DArena.test.cpp
new file mode 100644
index 0000000..2787047
--- /dev/null
+++ b/utest/DArena.test.cpp
@@ -0,0 +1,61 @@
+/** @file DArena.test.cpp
+ *
+ *  @author Roland Conybeare, Jan 2026
+ **/
+
+#include "xo/arena/DArena.hpp"
+#include <catch2/catch.hpp>
+
+namespace xo {
+    using xo::mm::DArena;
+    using xo::mm::ArenaConfig;
+    using std::byte;
+
+    namespace ut {
+        TEST_CASE("DArena-tiny", "[arena][DArena]")
+        {
+            ArenaConfig cfg { .name_ = "testarena",
+                              .size_ = 1 };
+            DArena arena = DArena::map(cfg);
+
+            REQUIRE(arena.config_.name_ == cfg.name_);
+            REQUIRE(arena.lo_ != nullptr);
+            REQUIRE(arena.free_ == arena.lo_);
+            REQUIRE(arena.limit_ == arena.lo_);
+            REQUIRE(arena.hi_ != nullptr);
+            REQUIRE(arena.hi_ > arena.lo_);
+            REQUIRE(((size_t)arena.hi_ - (size_t)arena.lo_) % arena.page_z_ == 0);
+            REQUIRE(arena.lo_ + cfg.size_ <= arena.hi_);
+
+            /* verify arena.lo_ is aligned on a page boundary */
+            REQUIRE(((size_t)(arena.lo_) & (arena.page_z_ - 1)) == 0);
+
+            /* verify arena.hi_ is aligned on a hugepage boundary */
+            REQUIRE(((size_t)(arena.hi_) & (arena.page_z_ - 1)) == 0);
+
+            byte * lo = arena.lo_;
+            byte * free = arena.free_;
+            byte * limit = arena.limit_;
+            byte * hi = arena.hi_;
+            size_t committed_z = arena.committed_z_;
+
+            DArena arena2 = std::move(arena);
+
+            REQUIRE(arena.lo_ == nullptr);
+            REQUIRE(arena.free_ == nullptr);
+            REQUIRE(arena.limit_ == nullptr);
+            REQUIRE(arena.hi_ == nullptr);
+            REQUIRE(arena.committed_z_ == 0);
+
+            REQUIRE(arena.lo_ == nullptr);
+            REQUIRE(arena2.lo_ == lo);
+            REQUIRE(arena2.free_ == free);
+            REQUIRE(arena2.limit_ == limit);
+            REQUIRE(arena2.hi_ == hi);
+            REQUIRE(arena2.committed_z_ == committed_z);
+        }
+
+    }
+}
+
+/* end DArena.test.cpp */
diff --git a/utest/arena_utest_main.cpp b/utest/arena_utest_main.cpp
new file mode 100644
index 0000000..e0fa95f
--- /dev/null
+++ b/utest/arena_utest_main.cpp
@@ -0,0 +1,6 @@
+/* file arena_utest_main.cpp */
+
+#define CATCH_CONFIG_MAIN
+#include "catch2/catch.hpp"
+
+/* end arena_utest_main.cpp */