Add test for umfPoolMallocUsableSize

Author: staniewzki

test/poolFixtures.hpp

@@ -456,4 +456,22 @@ TEST_P(umfPoolTest, allocMaxSize) {
     ASSERT_EQ(ptr, nullptr);
 }
 
+// Sanitizer replaces malloc_usable_size implementation with it's own,
+// what results in a failure.
+#ifndef __SANITIZE_ADDRESS__
+TEST_P(umfPoolTest, mallocUsableSize) {
+    for (size_t allocSize : {32, 48, 1024, 8192}) {
+        char *ptr = static_cast<char *>(umfPoolMalloc(pool.get(), allocSize));
+        size_t result = umfPoolMallocUsableSize(pool.get(), ptr);
+        EXPECT_TRUE(result == 0 or result >= allocSize);
+
+        for (size_t i = 0; i < result; i++) {
+            ptr[i] = 123;
+        }
+
+        umfPoolFree(pool.get(), ptr);
+    }
+}
+#endif
+
 #endif /* UMF_TEST_POOL_FIXTURES_HPP */