# Schema check: Columns and datatypes
def test_events_schema(events):
    expected_cols = {'request_id': np.object,
                     'item': np.object,
                     'position': np.int64,
                     'event_type': np.object}

    # Check all expected columns are present
    assert len(set(expected_cols.keys()) - set(events.columns)) == 0, \
        f'{set(expected_cols.keys()) - set(events.columns)} columns missing!'

    # Check all column data types are correct
    for col, dtype in expected_cols.items():
        assert events.dtypes[col] == dtype, \
            f'Expected column {col} to be of {dtype} type but found {events.dtypes[col]} type!'