def METHOD_NAME(mocker: MockFixture, pipeline_previewer):
    df_to_json_spy = mocker.spy(pd.DataFrame, "to_json")
    result = json.loads(
        pipeline_previewer(
            Pipeline(
                steps=[
                    {"name": "domain", "domain": "domain_a"},
                ]
            )
        )
    )
    assert "data" in result
    assert len(result["data"]) == 3  # rows
    assert len(result["data"][0]) == 3  # columns
    assert result["schema"]["fields"] == [
        {"name": "colA", "type": "string"},
        {"name": "colB", "type": "integer"},
        {"name": "colC", "type": "integer"},
    ]
    assert result["offset"] == 0
    assert result["limit"] == 50
    assert result["total"] == 3
    # DataFrames must be exported with pandas' method to ensure NaN and dates are correctly converted
    df_to_json_spy.assert_called_once()