diff --git a/pkg/ddc/alluxio/ufs_test.go b/pkg/ddc/alluxio/ufs_test.go
index a2bd72c0b1a..127ac6f8510 100644
--- a/pkg/ddc/alluxio/ufs_test.go
+++ b/pkg/ddc/alluxio/ufs_test.go
@@ -81,6 +81,9 @@ func TestUsedStorageBytes(t *testing.T) {
 	}
 }
 
+// TestFreeStorageBytes is a unit test for the AlluxioEngine.FreeStorageBytes method.
+// This test function defines a set of test cases, each including the expected return value and a flag indicating whether an error is expected.
+// The test invokes the FreeStorageBytes method and checks whether the returned value matches the expected result and whether error handling is performed correctly.
 func TestFreeStorageBytes(t *testing.T) {
 	type fields struct {
 	}