diff --git a/tests/util/test_common.h b/tests/util/test_common.h
new file mode 100644
index 0000000..56d5bab
--- /dev/null
+++ b/tests/util/test_common.h
@@ -0,0 +1,88 @@
+#ifndef TEST_COMMON_H
+#define TEST_COMMON_H
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <math.h>
+#include <time.h>
+
+#define TEST_PASSED 0
+#define TEST_FAILED 1
+
+typedef struct {
+    const char *name;
+    int (*fn)(void);
+} TestCase;
+
+typedef struct {
+    const char *name;
+    double (*fn)(void);
+} BenchCase;
+
+extern int test_failures;
+extern int test_total;
+
+#define TEST_ASSERT(cond, msg) do { \
+    if (!(cond)) { \
+        fprintf(stderr, "  [FAIL] %s\n", msg); \
+        test_failures++; \
+        return TEST_FAILED; \
+    } \
+} while (0)
+
+#define TEST_ASSERT_EQ(actual, expected, msg) do { \
+    if ((actual) != (expected)) { \
+        fprintf(stderr, "  [FAIL] %s: expected %ld, got %ld\n", msg, (long)(expected), (long)(actual)); \
+        test_failures++; \
+        return TEST_FAILED; \
+    } \
+} while (0)
+
+#define TEST_ASSERT_FTZ(actual, expected, tol, msg) do { \
+    double _diff = fabs((actual) - (expected)); \
+    if (_diff > (tol)) { \
+        fprintf(stderr, "  [FAIL] %s: expected %.6f, got %.6f (diff %.6f)\n", msg, (expected), (actual), _diff); \
+        test_failures++; \
+        return TEST_FAILED; \
+    } \
+} while (0)
+
+#define TEST_ASSERT_PTR_NOT_NULL(ptr, msg) do { \
+    if ((ptr) == NULL) { \
+        fprintf(stderr, "  [FAIL] %s: pointer is NULL\n", msg); \
+        test_failures++; \
+        return TEST_FAILED; \
+    } \
+} while (0)
+
+#define RUN_TEST(tests, name) do { \
+    int _result = (name)(); \
+    test_total++; \
+    if (_result == TEST_PASSED) { \
+        printf("  [PASS] %s\n", #name); \
+    } \
+} while (0)
+
+#define RUN_BENCH(benchmarks, name, iter) do { \
+    double _time = run_benchmark((name), (iter)); \
+    printf("  [BENCH] %-40s %.3f ms\n", #name, _time); \
+} while (0)
+
+extern int test_failures;
+extern int test_total;
+
+uint8_t *load_image(const char *path, int *width, int *height, int *channels);
+int save_image(const char *path, uint8_t *data, int width, int height, int channels);
+uint8_t *downsample_image(uint8_t *src, int sw, int sh, int sc, int *dw, int *dh, float scale);
+double get_time_ms(void);
+double run_benchmark(double (*fn)(void), int iterations);
+int compare_images(uint8_t *a, uint8_t *b, int w, int h, int ch, float threshold);
+float compute_psnr(uint8_t *a, uint8_t *b, int w, int h, int ch);
+uint8_t *create_gradient_image(int w, int h);
+uint8_t *create_noise_image(int w, int h, unsigned int seed);
+uint8_t *create_uniform_image(int w, int h, uint8_t r, uint8_t g, uint8_t b);
+uint8_t *create_checkerboard(int w, int h, int check_size);
+
+#endif