paimon-python/pypaimon/tests/execution_table_read_boundary_test.py

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"""Special-table APIs load backends only for operations that need them."""

import subprocess
import sys
import textwrap
from types import SimpleNamespace
from unittest.mock import Mock, patch

import pyarrow as pa


def test_importing_and_configuring_special_table_readers_is_lazy():
    result = subprocess.run(
        [sys.executable, "-c", textwrap.dedent("""
            import sys
            from pypaimon.table.format import FormatTableRead, FormatTableScan
            from pypaimon.table.object import ObjectTableRead, ObjectTableScan
            from pypaimon.table.system.system_table_read import SystemTableRead
            from pypaimon.table.system.system_table_scan import SystemTableScan

            table = object()
            FormatTableRead(table, projection=['id'], limit=1)
            FormatTableScan(table, partition_filter={'part': 'a'})
            ObjectTableRead(table, projection=['name'], limit=1)
            ObjectTableScan(table)
            SystemTableRead(table, [], predicate=None, limit=1)
            SystemTableScan(table)
            for module in (
                'format_table_read', 'format_table_scan',
                'object_table_read', 'object_table_scan',
            ):
                assert 'pypaimon.execution.python.read.' + module not in sys.modules, module
            assert 'pypaimon_rust' not in sys.modules
        """)],
        capture_output=True, text=True,
    )
    assert result.returncode == 0, result.stderr


def test_native_system_scan_never_materializes_the_python_provider():
    from pypaimon.table.system.system_table_scan import SystemSplit, SystemTableScan

    rows = pa.table({'id': [7, 11]})
    provider = SimpleNamespace(
        _build_arrow_table=Mock(side_effect=AssertionError('Python provider')),
        base_table=SimpleNamespace(options=SimpleNamespace(native_read_enabled=lambda: True)),
    )
    with patch('pypaimon.execution.native.read.system_table.try_read_native_system_table', return_value=rows):
        plan = SystemTableScan(provider).plan()
    provider._build_arrow_table.assert_not_called()
    split, = plan.splits()
    assert isinstance(split, SystemSplit)
    assert split.arrow_table().equals(rows)


def test_python_system_scan_materializes_once_and_keeps_the_public_split():
    from pypaimon.table.system.system_table_scan import SystemSplit, SystemTableScan

    rows = pa.table({'id': [3]})
    provider = SimpleNamespace(_build_arrow_table=Mock(return_value=rows))
    with patch('pypaimon.execution.native.read.system_table.try_read_native_system_table', return_value=None):
        plan = SystemTableScan(provider).plan()
    provider._build_arrow_table.assert_called_once_with()
    split, = plan.splits()
    assert isinstance(split, SystemSplit)
    assert split.arrow_table().equals(rows)