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Validating Topological Sort Algorithm Implementation in javascript-algorithms

This test suite validates the implementation of topological sorting algorithm on a directed graph structure. It verifies the correct ordering of vertices based on their dependencies, ensuring that for each directed edge u→v, vertex u comes before v in the ordering.

Test Coverage Overview

The test suite provides comprehensive coverage of the topological sort implementation by creating a complex directed graph with multiple vertices and edges.

Tests vertex ordering in a directed acyclic graph (DAG)
Validates the output length matches total vertices
Verifies correct sequential ordering of dependent vertices
Covers graph construction and edge relationships

Implementation Analysis

The testing approach uses Jest’s describe/it pattern to structure the test cases. A directed graph is constructed programmatically with 8 vertices (A-H) and their corresponding edges to create a complex dependency network.

The test utilizes Graph, GraphVertex, and GraphEdge classes to build the test scenario, demonstrating proper object-oriented testing patterns.

Technical Details

Testing Framework: Jest
Data Structures: Graph, GraphVertex, GraphEdge
Assertion Methods: expect().toBeDefined(), expect().toBe(), expect().toEqual()
Test Setup: Individual vertex and edge creation followed by graph construction

Best Practices Demonstrated

The test exhibits several testing best practices including clear arrangement of test components and explicit expected outcomes.

Systematic graph construction with clear vertex and edge definitions
Multiple assertion points to validate different aspects
Clear test case isolation and setup
Readable and maintainable test structure

trekhleb/javascript-algorithms

src/algorithms/graph/topological-sorting/__test__/topologicalSort.test.js

            
import GraphVertex from '../../../../data-structures/graph/GraphVertex';
import GraphEdge from '../../../../data-structures/graph/GraphEdge';
import Graph from '../../../../data-structures/graph/Graph';
import topologicalSort from '../topologicalSort';

describe('topologicalSort', () => {
  it('should do topological sorting on graph', () => {
    const vertexA = new GraphVertex('A');
    const vertexB = new GraphVertex('B');
    const vertexC = new GraphVertex('C');
    const vertexD = new GraphVertex('D');
    const vertexE = new GraphVertex('E');
    const vertexF = new GraphVertex('F');
    const vertexG = new GraphVertex('G');
    const vertexH = new GraphVertex('H');

    const edgeAC = new GraphEdge(vertexA, vertexC);
    const edgeBC = new GraphEdge(vertexB, vertexC);
    const edgeBD = new GraphEdge(vertexB, vertexD);
    const edgeCE = new GraphEdge(vertexC, vertexE);
    const edgeDF = new GraphEdge(vertexD, vertexF);
    const edgeEF = new GraphEdge(vertexE, vertexF);
    const edgeEH = new GraphEdge(vertexE, vertexH);
    const edgeFG = new GraphEdge(vertexF, vertexG);

    const graph = new Graph(true);

    graph
      .addEdge(edgeAC)
      .addEdge(edgeBC)
      .addEdge(edgeBD)
      .addEdge(edgeCE)
      .addEdge(edgeDF)
      .addEdge(edgeEF)
      .addEdge(edgeEH)
      .addEdge(edgeFG);

    const sortedVertices = topologicalSort(graph);

    expect(sortedVertices).toBeDefined();
    expect(sortedVertices.length).toBe(graph.getAllVertices().length);
    expect(sortedVertices).toEqual([
      vertexB,
      vertexD,
      vertexA,
      vertexC,
      vertexE,
      vertexH,
      vertexF,
      vertexG,
    ]);
  });
});