algorithms-and-data-structures/AlgorithmsAndDataStructures.Tests/Algorithm/Graph/CycleDetectionTests.cs at master · arst/algorithms-and-data-structures · GitHub

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using System.Collections.Generic;
using AlgorithmsAndDataStructures.Algorithms.Graph.Misc;
using AlgorithmsAndDataStructures.DataStructures.Graph;
using Xunit;

namespace AlgorithmsAndDataStructures.Tests.Algorithm.Graph;

public class CycleDetectionTests
{
    [Fact]
    public void SelfCycleIsDetected()
    {
        var graph = new[]
        {
            new GraphVertex<int>
            {
                Value = 1,
                AdjacentVertices = new List<int> { 0 }
            }
        };

        Assert.True(CycleDetector.IsCyclic(graph));
    }

    [Fact]
    public void SimpleTwoNodeCycleIsDetected()
    {
        var graph = new[]
        {
            new GraphVertex<int>
            {
                Value = 1,
                AdjacentVertices = new List<int> { 1 }
            },
            new GraphVertex<int>
            {
                Value = 2,
                AdjacentVertices = new List<int> { 0 }
            }
        };

        Assert.True(CycleDetector.IsCyclic(graph));
    }

    [Fact]
    public void CycleIsNotDetectedForNonCycledGraph()
    {
        var graph = new[]
        {
            new GraphVertex<int>
            {
                Value = 1,
                AdjacentVertices = new List<int> { 1 }
            },
            new GraphVertex<int>
            {
                Value = 2
            }
        };

        Assert.False(CycleDetector.IsCyclic(graph));
    }

    [Fact]
    public void DisconnectedGraphCycleIsDetected()
    {
        var graph = new[]
        {
            new GraphVertex<int>
            {
                Value = 1
            },
            new GraphVertex<int>
            {
                Value = 2,
                AdjacentVertices = new List<int> { 2 }
            },
            new GraphVertex<int>
            {
                Value = 2,
                AdjacentVertices = new List<int> { 1 }
            }
        };

        Assert.True(CycleDetector.IsCyclic(graph));
    }

    [Fact]
    public void DisconnectedGraphWithMultipleCyclesIsDetected()
    {
        var graph = new[]
        {
            new GraphVertex<int>
            {
                Value = 1,
                AdjacentVertices = new List<int> { 1, 2 }
            },
            new GraphVertex<int>
            {
                Value = 2,
                AdjacentVertices = new List<int> { 2 }
            },
            new GraphVertex<int>
            {
                Value = 2,
                AdjacentVertices = new List<int> { 0, 3 }
            },
            new GraphVertex<int>
            {
                Value = 2,
                AdjacentVertices = new List<int> { 3 }
            }
        };

        Assert.True(CycleDetector.IsCyclic(graph));
    }
}