test(ethexe-runtime-common): repro for stale region hash on full-region clear (auto-tester) — refs #5373

ethexe/runtime/common/tests/auto_tester_a07d9f041168.rs

@@ -0,0 +1,50 @@
+// auto_tester_a07d9f041168
+// scenario: invalid_combination
+// param_signature: remove_and_store_regions stale region hash on full region clear
+
+// Reproduces the bug tracked by `// TODO #5373` at ethexe/runtime/common/src/state.rs:1057-1062.
+// Closed upstream issue: https://github.com/gear-tech/gear/issues/5373
+//
+// When `remove_and_store_regions` empties a region (last page removed),
+// `region.store(storage)` returns `MaybeHashOf::empty()`. The if-let in the
+// update loop then never fires, so `self[region_idx]` keeps its old
+// (non-empty) hash — the MemoryPages aggregate hash is stale.
+//
+// Expected: removing the only page in a region must change the MemoryPages
+// hash (the region is no longer represented by its old content hash).
+// Observed: hash before == hash after.
+
+use ethexe_runtime_common::state::{MemStorage, MemoryPages, Storage};
+use gear_core::{memory::PageBuf, pages::GearPage};
+use std::collections::BTreeMap;
+
+#[test]
+fn remove_last_page_in_region_must_clear_region_hash() {
+    let storage = MemStorage::default();
+    let mut pages = MemoryPages::default();
+
+    // Add one page to region 0.
+    let page0 = GearPage::from(0u16);
+    let buf = PageBuf::new_zeroed();
+    let page_hash = storage.write_page_data(buf);
+
+    let mut page_map = BTreeMap::new();
+    page_map.insert(page0, page_hash);
+    pages.update_and_store_regions(&storage, page_map);
+
+    let hash_with_page = pages.clone().store(&storage).to_inner();
+
+    // Remove the only page — region 0 is now empty.
+    pages.remove_and_store_regions(&storage, &vec![page0]);
+
+    let hash_after_remove = pages.clone().store(&storage).to_inner();
+
+    // The aggregate hash MUST change: an empty region is observationally
+    // different from a region holding one page.
+    assert_ne!(
+        hash_with_page, hash_after_remove,
+        "MemoryPages hash must change when the last page in a region is removed; \
+         see TODO #5373 in state.rs:1057-1062 (the if-let skips empty regions \
+         and leaves a stale region hash in self[region_idx])"
+    );
+}