From 4747b0f686e9e2c5aad29d5a8726ebc3dbb3156d Mon Sep 17 00:00:00 2001
From: osipovartem <artemosipov.dev@gmail.com>
Date: Thu, 15 Oct 2026 11:15:37 +0300
Subject: [PATCH] test: verify changed-file scans skip unchanged data files

---
 datafusion_iceberg/src/table/mod.rs | 30 +++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/datafusion_iceberg/src/table/mod.rs b/datafusion_iceberg/src/table/mod.rs
index 86f8017f..67cb62f6 100644
--- a/datafusion_iceberg/src/table/mod.rs
+++ b/datafusion_iceberg/src/table/mod.rs
@@ -3295,6 +3295,36 @@ mod tests {
             None,
             Some(changes_config),
         ));
+        fn planned_data_file_count(plan: &dyn ExecutionPlan) -> usize {
+            let current = plan
+                .downcast_ref::<DataSourceExec>()
+                .and_then(|exec| exec.data_source().downcast_ref::<FileScanConfig>())
+                .map(|config| {
+                    config
+                        .file_groups
+                        .iter()
+                        .map(|group| group.files().len())
+                        .sum::<usize>()
+                })
+                .unwrap_or_default();
+            current
+                + plan
+                    .children()
+                    .iter()
+                    .map(|child| planned_data_file_count(child.as_ref()))
+                    .sum::<usize>()
+        }
+        let full_plan = writable
+            .scan(&ctx.state(), None, &[], None)
+            .await
+            .expect("plan full v3 scan");
+        let changes_plan = changes
+            .scan(&ctx.state(), None, &[], None)
+            .await
+            .expect("plan changed-file scan");
+        assert_eq!(planned_data_file_count(full_plan.as_ref()), 3);
+        assert_eq!(planned_data_file_count(changes_plan.as_ref()), 2);
+
         ctx.deregister_table("lineage_numbers")
             .expect("deregister writable table");
         ctx.register_table("lineage_numbers", changes)