code: def test_read_sql_source_combination(  # noqa: D
      request: FixtureRequest,
      mf_test_session_state: MetricFlowTestSessionState,
      consistent_id_object_repository: ConsistentIdObjectRepository,
  ) -> None:
      """Tests combining a single node."""
      source0 = consistent_id_object_repository.simple_model_read_nodes[
          "bookings_source"
      ]
      source1 = consistent_id_object_repository.simple_model_read_nodes[
          "bookings_source"
      ]
      combiner = ComputeMetricsBranchCombiner(source0)
  
      result: ComputeMetricsBranchCombinerResult = source1.accept(
          combiner
      )
      assert result.combined_branch
  
      dataflow_plan = make_dataflow_plan(result.combined_branch)
      assert_plan_snapshot_text_equal(
          request=request,
          mf_test_session_state=mf_test_session_state,
          plan=dataflow_plan,
          plan_snapshot_text=dataflow_plan_as_text(dataflow_plan),
      )
  
      display_graph_if_requested(
          request=request,
          mf_test_session_state=mf_test_session_state,
          dag_graph=dataflow_plan,
      )
  
file_path: metricflow/metricflow/test/dataflow/optimizer/source_scan/test_cm_branch_combiner.py
imports: from __future__ import annotations
  import pytest
  from _pytest.fixtures import FixtureRequest
  from metricflow.dag.id_generation import OPTIMIZED_DATAFLOW_PLAN_PREFIX, IdGeneratorRegistry
  from metricflow.dataflow.dataflow_plan import BaseOutput, DataflowPlan, FilterElementsNode, WriteToResultDataframeNode
  from metricflow.dataflow.dataflow_plan_to_text import dataflow_plan_as_text
  from metricflow.dataflow.optimizer.source_scan.cm_branch_combiner import ComputeMetricsBranchCombiner, ComputeMetricsBranchCombinerResult
  from metricflow.specs.specs import InstanceSpecSet, MeasureSpec
  from metricflow.test.dataflow_plan_to_svg import display_graph_if_requested
  from metricflow.test.fixtures.model_fixtures import ConsistentIdObjectRepository
  from metricflow.test.fixtures.setup_fixtures import MetricFlowTestSessionState
  from metricflow.test.snapshot_utils import assert_plan_snapshot_text_equal
label_desc: Use image node_id 2 for calling a global function with example usage: test_read_sql_source_combination(request, mf_test_session_state, consistent_id_object_repository) without return types