doc: Document test_free().
diff --git a/include/cmocka.h b/include/cmocka.h
index abde7f5..6c96bea 100755
--- a/include/cmocka.h
+++ b/include/cmocka.h
@@ -816,7 +816,18 @@
#define test_calloc(num, size) _test_calloc(num, size, __FILE__, __LINE__)
#endif
+#ifdef DOXYGEN
+/**
+ * @brief Test function overriding free(3).
+ *
+ * @param[in] ptr The pointer to the memory space to free.
+ *
+ * @see free(3).
+ */
+void test_free(void *ptr);
+#else
#define test_free(ptr) _test_free(ptr, __FILE__, __LINE__)
+#endif
/* Redirect malloc, calloc and free to the unit test allocators. */
#if UNIT_TESTING
