Validate cached models against remote generation identities

tests/large_file/test_cache_generations.py

@@ -0,0 +1,46 @@
+from hashlib import sha256
+from pathlib import Path
+from typing import Any, Dict
+from unittest.mock import MagicMock, patch
+
+from great_ai.large_file import LargeFileS3
+
+
+def test_recreated_remote_version_invalidates_other_clients(tmp_path: Path) -> None:
+    remote: Dict[str, bytes] = {}
+    backend = MagicMock()
+    backend.list_objects_v2.side_effect = lambda **kwargs: {
+        "Contents": [
+            {"Key": key, "ETag": sha256(value).hexdigest()}
+            for key, value in remote.items()
+        ]
+    }
+    backend.delete_object.side_effect = lambda **kwargs: remote.pop(kwargs["Key"])
+
+    def upload(self: LargeFileS3, path: Path, hide_progress: bool) -> None:
+        remote[f"{self._name}/{self.version}"] = path.read_bytes()
+
+    def download(
+        self: LargeFileS3, remote_path: Any, path: Path, hide_progress: bool
+    ) -> None:
+        path.write_bytes(remote[remote_path])
+
+    with (
+        patch.object(LargeFileS3, "_client", backend),
+        patch.object(LargeFileS3, "_upload", upload),
+        patch.object(LargeFileS3, "_download", download),
+        patch.object(LargeFileS3, "max_cache_size", None),
+    ):
+        with patch.object(LargeFileS3, "cache_path", tmp_path / "writer"):
+            with LargeFileS3("model", "w") as file:
+                file.write("old")
+        with patch.object(LargeFileS3, "cache_path", tmp_path / "reader"):
+            reader = LargeFileS3("model")
+            assert reader.get().read_text() == "old"
+        with patch.object(LargeFileS3, "cache_path", tmp_path / "writer"):
+            LargeFileS3("model").delete()
+            with LargeFileS3("model", "w") as file:
+                file.write("new")
+            assert LargeFileS3("model").get().read_text() == "new"
+        with patch.object(LargeFileS3, "cache_path", tmp_path / "reader"):
+            assert reader.get().read_text() == "new"