diff --git a/tests/arena_test.cpp b/tests/arena_test.cpp
new file mode 100644
index 0000000..f012183
--- /dev/null
+++ b/tests/arena_test.cpp
@@ -0,0 +1,163 @@
+#include <gtest/gtest.h>
+#include <random>
+#include "mimir.h"
+
+#include "test_util.h"
+
+namespace mimir_tests {
+
+TEST(Arena, OutOfMemory)
+{
+  mimir::init();
+  mimir::Arena arena;
+  EXPECT_TRUE(arena.init(1ULL << 24, 1ULL << 46));
+  EXPECT_TRUE(arena.alloc(1ULL << 49) == nullptr);
+}
+
+TEST(Arena, Overflow)
+{
+  mimir::init();
+  mimir::Arena arena;
+  EXPECT_TRUE(arena.init(128, 1024));
+  EXPECT_TRUE(arena.alloc(512) != nullptr);
+  EXPECT_TRUE(arena.alloc(512) != nullptr);
+  EXPECT_TRUE(arena.alloc(arena.getMaxSize() - 1024 + 1) == nullptr);
+}
+
+TEST(Arena, Alignment16)
+{
+  mimir::init();
+  mimir::Arena arena;
+  EXPECT_TRUE(arena.init());
+
+  for (int i = 0; i < 128; i++) {
+    for (int j = 1; j < 128; j++) {
+      EXPECT_TRUE(arena.alloc(i) != nullptr);
+      for (int k = 0; k < 16; k++) {
+        std::byte* addr = arena.allocA16(j);
+        EXPECT_TRUE(addr != nullptr);
+        EXPECT_EQ((size_t)addr & 0b1111, 0);
+        EXPECT_EQ(arena.getUsed() & 0b1111, 0);
+      }
+      arena.reset();
+    }
+  }
+}
+
+TEST(Arena, Alignment64)
+{
+  mimir::init();
+  mimir::Arena arena;
+  EXPECT_TRUE(arena.init());
+
+  for (int i = 0; i < 128; i++) {
+    for (int j = 1; j < 128; j++) {
+      EXPECT_TRUE(arena.alloc(i) != nullptr);
+      for (int k = 0; k < 16; k++) {
+        std::byte* addr = arena.allocA64(j);
+        EXPECT_TRUE(addr != nullptr);
+        EXPECT_EQ((size_t)addr & 0b111111, 0);
+        EXPECT_EQ(arena.getUsed() & 0b111111, 0);
+      }
+      arena.reset();
+    }
+  }
+}
+
+TEST(Arena, OverflowByAlignmentA16)
+{
+  mimir::init();
+  mimir::Arena arena;
+  EXPECT_TRUE(arena.init(128, 1024));
+
+  // Controlled test - first try with no alignment. This should pass.
+  EXPECT_TRUE(arena.alloc(alignDown(arena.getMaxSize(), 16) - 15) != nullptr);
+  EXPECT_TRUE(arena.alloc(arena.getMaxSize() - arena.getUsed()) != nullptr);
+  arena.reset();
+
+  // Now try with allocA16. This should fail.
+  EXPECT_TRUE(arena.alloc(alignDown(arena.getMaxSize(), 16) - 15) != nullptr);
+  EXPECT_TRUE(arena.allocA16(arena.getMaxSize() - arena.getUsed()) == nullptr);
+}
+
+TEST(Arena, OverflowByAlignmentA64)
+{
+  mimir::init();
+  mimir::Arena arena;
+  EXPECT_TRUE(arena.init(128, 1024));
+
+  // Controlled test - first try with no alignment. This should pass.
+  EXPECT_TRUE(arena.alloc(alignDown(arena.getMaxSize(), 64) - 63) != nullptr);
+  EXPECT_TRUE(arena.alloc(arena.getMaxSize() - arena.getUsed()) != nullptr);
+  arena.reset();
+
+  // Now try with allocA64. This should fail.
+  EXPECT_TRUE(arena.alloc(alignDown(arena.getMaxSize(), 64) - 63) != nullptr);
+  EXPECT_TRUE(arena.allocA64(arena.getMaxSize() - arena.getUsed()) == nullptr);
+}
+
+TEST(Arena, ArenaFillAndReset)
+{
+  // We purposefully want to have the same random sequence each time
+
+  const int maxAllocCount = 128;
+  const int cycleCount = 128;
+  std::mt19937_64 rgen(1234);
+  std::uniform_int_distribution<int> count_dist(0, maxAllocCount);
+  std::uniform_int_distribution<size_t> alloc_dist1(1, 256);
+  std::uniform_int_distribution<size_t> alloc_dist2(1, 1024 * 256);
+  std::uniform_int_distribution<size_t> alloc_dist3(1, 1024 * 1024 * 256);
+
+  mimir::init();
+  mimir::Arena arena;
+  EXPECT_TRUE(arena.init(0, 1ULL << 32)); // Use up to 4GB
+  size_t allocSize[maxAllocCount];
+  std::byte* allocAddr[maxAllocCount];
+
+  for (int i = 0; i < cycleCount; i++) {
+    int allocCount = 0;
+    if (i != 5) {
+      // Make sure at least one cycle has 0 allocations
+      allocCount = count_dist(rgen);
+    }
+    for (int j = 0; j < allocCount; j++) {
+      allocSize[j] = alloc_dist1(rgen);
+    }
+    for (int j = 0; j < 32; j++) {
+      int k = count_dist(rgen);
+      if (k < allocCount) {
+        allocSize[k] = alloc_dist2(rgen);
+      }
+    }
+    
+    for (int j = 0; j < 3; j++) {
+      int k = count_dist(rgen);
+      if (k < allocCount) {
+        allocSize[k] = alloc_dist3(rgen);
+      }
+    }
+
+    size_t totalSize = 0;
+    for (int j = 0; j < allocCount; j++) {
+      totalSize += allocSize[j];
+      allocAddr[j] = arena.alloc(allocSize[j]);
+      EXPECT_TRUE(allocAddr[j] != nullptr);
+      if (allocAddr[j] != nullptr) {
+        writeData(allocAddr[j], allocSize[j], j);
+      }
+    }
+
+    for (int j = 0; j < allocCount; j++) {
+      if (allocAddr[j] != nullptr) {
+        EXPECT_TRUE(checkData(allocAddr[j], allocSize[j], j));
+      }
+    }
+
+    EXPECT_EQ(arena.getUsed(), totalSize);
+
+    arena.reset();
+    EXPECT_EQ(arena.getUsed(), 0);
+  }
+}
+
+}; // namespace mimir_tests
diff --git a/tests/test_util.cpp b/tests/test_util.cpp
new file mode 100644
index 0000000..535bdc8
--- /dev/null
+++ b/tests/test_util.cpp
@@ -0,0 +1,49 @@
+#include "test_util.h"
+
+#include <algorithm>
+
+namespace mimir_tests {
+
+const size_t kPatternLen = 32;
+
+void getPattern(std::byte* pattern, int seed)
+{
+  for (int i = 0; i < kPatternLen; i++) {
+    pattern[i] = std::byte((seed * 3162 + i * 63163) % 0xff);
+  }
+}
+
+void writeData(std::byte* dest, size_t count, int seed)
+{
+  std::byte pattern[kPatternLen];
+  getPattern(pattern, seed);
+
+  for (int i = 0; i < count; i += kPatternLen) {
+    memcpy(dest + i, pattern, std::min(count - i, kPatternLen));
+  }
+}
+
+bool checkData(std::byte* src, size_t count, int seed)
+{
+  std::byte pattern[kPatternLen];
+  getPattern(pattern, seed);
+
+  for (int i = 0; i < count; i += kPatternLen) {
+    if (memcmp(src + i, pattern, std::min(count - i, kPatternLen)) != 0) {
+      return false;
+    }
+  }
+  return true;
+}
+
+size_t alignUp(size_t val, size_t alignment)
+{
+  return alignDown(val - 1, alignment) + alignment;
+}
+
+size_t alignDown(size_t val, size_t alignment)
+{
+  return val & ~(alignment - 1);
+}
+
+}; // namespace mimir_tests
diff --git a/tests/test_util.h b/tests/test_util.h
new file mode 100644
index 0000000..223b9e0
--- /dev/null
+++ b/tests/test_util.h
@@ -0,0 +1,12 @@
+#pragma once
+
+#include <cstddef>
+
+namespace mimir_tests {
+
+void writeData(std::byte* dest, size_t count, int seed);
+bool checkData(std::byte* src, size_t count, int seed);
+size_t alignUp(size_t val, size_t alignment);
+size_t alignDown(size_t val, size_t alignment);
+
+}; // namespace mimir_tests