paimon-python/pypaimon/tests/snapshot_manager_test.py

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"""
Tests for SnapshotManager batch lookahead functionality.
"""

import unittest
from unittest.mock import Mock


def _create_mock_snapshot(snapshot_id: int, commit_kind: str = "APPEND"):
    """Helper to create a mock snapshot."""
    from pypaimon.snapshot.snapshot import Snapshot
    snapshot = Mock(spec=Snapshot)
    snapshot.id = snapshot_id
    snapshot.commit_kind = commit_kind
    snapshot.time_millis = 1000000 + snapshot_id
    return snapshot


def _build_manager(file_io):
    from pypaimon.snapshot.snapshot_manager import SnapshotManager
    return SnapshotManager(file_io, "/tmp/test_table")


class SnapshotManagerTest(unittest.TestCase):
    """Tests for SnapshotManager batch lookahead methods."""

    def test_find_next_scannable_returns_first_matching(self):
        """find_next_scannable should return the first snapshot that passes should_scan."""
        file_io = Mock()
        file_io.exists_batch.return_value = {
            "/tmp/test_table/snapshot/snapshot-5": True,
            "/tmp/test_table/snapshot/snapshot-6": True,
            "/tmp/test_table/snapshot/snapshot-7": True,
        }

        snapshots = {
            5: _create_mock_snapshot(5, "COMPACT"),
            6: _create_mock_snapshot(6, "COMPACT"),
            7: _create_mock_snapshot(7, "APPEND"),
        }

        manager = _build_manager(file_io)
        manager.get_snapshot_by_id = lambda sid: snapshots.get(sid)

        def should_scan(snapshot):
            return snapshot.commit_kind == "APPEND"

        result, next_id, skipped_count = manager.find_next_scannable(5, should_scan, lookahead_size=5)

        self.assertEqual(result.id, 7)
        self.assertEqual(next_id, 8)
        self.assertEqual(skipped_count, 2)

    def test_find_next_scannable_returns_none_when_no_snapshot_exists(self):
        """find_next_scannable should return None when no snapshot exists at start_id."""
        file_io = Mock()
        file_io.exists_batch.return_value = {}

        manager = _build_manager(file_io)

        def should_scan(snapshot):
            return True

        result, next_id, skipped_count = manager.find_next_scannable(5, should_scan, lookahead_size=5)

        self.assertIsNone(result)
        self.assertEqual(next_id, 5)
        self.assertEqual(skipped_count, 0)

    def test_find_next_scannable_continues_when_all_skipped(self):
        """When all lookahead snapshots are skipped, next_id should be start+lookahead."""
        file_io = Mock()
        file_io.exists_batch.return_value = {
            "/tmp/test_table/snapshot/snapshot-5": True,
            "/tmp/test_table/snapshot/snapshot-6": True,
            "/tmp/test_table/snapshot/snapshot-7": True,
        }

        snapshots = {
            5: _create_mock_snapshot(5, "COMPACT"),
            6: _create_mock_snapshot(6, "COMPACT"),
            7: _create_mock_snapshot(7, "COMPACT"),
        }

        manager = _build_manager(file_io)
        manager.get_snapshot_by_id = lambda sid: snapshots.get(sid)

        def should_scan(snapshot):
            return snapshot.commit_kind == "APPEND"

        result, next_id, skipped_count = manager.find_next_scannable(5, should_scan, lookahead_size=3)

        self.assertIsNone(result)
        self.assertEqual(next_id, 8)
        self.assertEqual(skipped_count, 3)


if __name__ == '__main__':
    unittest.main()