grafana/public/app/core/utils/dag.test.ts

import { Graph } from './dag';

describe('Directed acyclic graph', () => {
  describe('Given a graph with nodes with different links in between them', () => {
    const dag = new Graph();
    const nodeA = dag.createNode('A');
    const nodeB = dag.createNode('B');
    const nodeC = dag.createNode('C');
    const nodeD = dag.createNode('D');
    const nodeE = dag.createNode('E');
    const nodeF = dag.createNode('F');
    const nodeG = dag.createNode('G');
    const nodeH = dag.createNode('H');
    const nodeI = dag.createNode('I');
    dag.link([nodeB, nodeC, nodeD, nodeE, nodeF, nodeG, nodeH], nodeA);
    dag.link([nodeC, nodeD, nodeE, nodeF, nodeI], nodeB);
    dag.link([nodeD, nodeE, nodeF, nodeG], nodeC);
    dag.link([nodeE, nodeF], nodeD);
    dag.link([nodeF, nodeG], nodeE);
    //printGraph(dag);

    it('nodes in graph should have expected edges', () => {
      expect(nodeA.inputEdges).toHaveLength(7);
      expect(nodeA.outputEdges).toHaveLength(0);
      expect(nodeA.edges).toHaveLength(7);

      expect(nodeB.inputEdges).toHaveLength(5);
      expect(nodeB.outputEdges).toHaveLength(1);
      expect(nodeB.edges).toHaveLength(6);

      expect(nodeC.inputEdges).toHaveLength(4);
      expect(nodeC.outputEdges).toHaveLength(2);
      expect(nodeC.edges).toHaveLength(6);

      expect(nodeD.inputEdges).toHaveLength(2);
      expect(nodeD.outputEdges).toHaveLength(3);
      expect(nodeD.edges).toHaveLength(5);

      expect(nodeE.inputEdges).toHaveLength(2);
      expect(nodeE.outputEdges).toHaveLength(4);
      expect(nodeE.edges).toHaveLength(6);

      expect(nodeF.inputEdges).toHaveLength(0);
      expect(nodeF.outputEdges).toHaveLength(5);
      expect(nodeF.edges).toHaveLength(5);

      expect(nodeG.inputEdges).toHaveLength(0);
      expect(nodeG.outputEdges).toHaveLength(3);
      expect(nodeG.edges).toHaveLength(3);

      expect(nodeH.inputEdges).toHaveLength(0);
      expect(nodeH.outputEdges).toHaveLength(1);
      expect(nodeH.edges).toHaveLength(1);

      expect(nodeI.inputEdges).toHaveLength(0);
      expect(nodeI.outputEdges).toHaveLength(1);
      expect(nodeI.edges).toHaveLength(1);

      expect(nodeA.getEdgeFrom(nodeB)).not.toBeUndefined();
      expect(nodeB.getEdgeTo(nodeA)).not.toBeUndefined();
    });

    it('when optimizing input edges for node A should return node B and H', () => {
      const actual = nodeA.getOptimizedInputEdges().map((e) => e.inputNode);
      expect(actual).toHaveLength(2);
      expect(actual).toEqual(expect.arrayContaining([nodeB, nodeH]));
    });

    it('when optimizing input edges for node B should return node C', () => {
      const actual = nodeB.getOptimizedInputEdges().map((e) => e.inputNode);
      expect(actual).toHaveLength(2);
      expect(actual).toEqual(expect.arrayContaining([nodeC, nodeI]));
    });

    it('when optimizing input edges for node C should return node D', () => {
      const actual = nodeC.getOptimizedInputEdges().map((e) => e.inputNode);
      expect(actual).toHaveLength(1);
      expect(actual).toEqual(expect.arrayContaining([nodeD]));
    });

    it('when optimizing input edges for node D should return node E', () => {
      const actual = nodeD.getOptimizedInputEdges().map((e) => e.inputNode);
      expect(actual).toHaveLength(1);
      expect(actual).toEqual(expect.arrayContaining([nodeE]));
    });

    it('when optimizing input edges for node E should return node F and G', () => {
      const actual = nodeE.getOptimizedInputEdges().map((e) => e.inputNode);
      expect(actual).toHaveLength(2);
      expect(actual).toEqual(expect.arrayContaining([nodeF, nodeG]));
    });

    it('when optimizing input edges for node F should return zero nodes', () => {
      const actual = nodeF.getOptimizedInputEdges();
      expect(actual).toHaveLength(0);
    });

    it('when optimizing input edges for node G should return zero nodes', () => {
      const actual = nodeG.getOptimizedInputEdges();
      expect(actual).toHaveLength(0);
    });

    it('when optimizing input edges for node H should return zero nodes', () => {
      const actual = nodeH.getOptimizedInputEdges();
      expect(actual).toHaveLength(0);
    });

    it('when linking non-existing input node with existing output node should throw error', () => {
      expect(() => {
        dag.link('non-existing', 'A');
      }).toThrowError("cannot link input node named non-existing since it doesn't exist in graph");
    });

    it('when linking existing input node with non-existing output node should throw error', () => {
      expect(() => {
        dag.link('A', 'non-existing');
      }).toThrowError("cannot link output node named non-existing since it doesn't exist in graph");
    });
  });
});