Rendezvous/tests/FinalFactory.Rendezvous.Tests/Architecture/DependencyBoundaryTests.cs

using System.Reflection;
using System.Xml.Linq;

namespace FinalFactory.Rendezvous.Tests.Architecture;

public sealed class DependencyBoundaryTests
{
    [Fact]
    public void ContractsAreTransportAndEngineIndependent()
    {
        string[] references = GetReferences("FinalFactory.Rendezvous.Contracts");

        Assert.DoesNotContain(references, IsGodotAssembly);
        Assert.DoesNotContain(references, IsServerAssembly);
        Assert.DoesNotContain(references, IsLiteNetLibAssembly);
    }

    [Fact]
    public void ClientIsGodotAndServerIndependent()
    {
        string[] references = GetReferences("FinalFactory.Rendezvous.Client");

        Assert.DoesNotContain(references, IsGodotAssembly);
        Assert.DoesNotContain(references, IsServerAssembly);
    }

    [Fact]
    public void TestClientUsesOnlyPublicRendezvousDependencies()
    {
        string[] references = GetReferences("FinalFactory.Rendezvous.TestClient");

        Assert.DoesNotContain(references, IsGodotAssembly);
        Assert.DoesNotContain(references, IsServerAssembly);
    }

    [Fact]
    public void DeclaredDependencyGraphMatchesTheArchitecture()
    {
        AssertDeclaredDependencies(
            "src/FinalFactory.Rendezvous.Contracts/FinalFactory.Rendezvous.Contracts.csproj",
            [],
            []);
        AssertDeclaredDependencies(
            "src/FinalFactory.Rendezvous.Client/FinalFactory.Rendezvous.Client.csproj",
            ["FinalFactory.Rendezvous.Contracts"],
            ["LiteNetLib"]);
        AssertDeclaredDependencies(
            "src/FinalFactory.Rendezvous.Server/FinalFactory.Rendezvous.Server.csproj",
            ["FinalFactory.Rendezvous.Contracts"],
            ["LiteNetLib"]);
        AssertDeclaredDependencies(
            "src/FinalFactory.Rendezvous.TestClient/FinalFactory.Rendezvous.TestClient.csproj",
            ["FinalFactory.Rendezvous.Client", "FinalFactory.Rendezvous.Contracts"],
            ["LiteNetLib"]);
    }

    private static void AssertDeclaredDependencies(
        string projectPath,
        string[] expectedProjects,
        string[] expectedPackages)
    {
        XDocument project = XDocument.Load(Path.Combine(FindRepositoryRoot(), projectPath));
        string[] projects = project
            .Descendants("ProjectReference")
            .Select(static element =>
                Path.GetFileNameWithoutExtension(element.Attribute("Include")?.Value) ?? string.Empty)
            .Order(StringComparer.Ordinal)
            .ToArray();
        string[] packages = project
            .Descendants("PackageReference")
            .Select(static element => element.Attribute("Include")?.Value ?? string.Empty)
            .Order(StringComparer.Ordinal)
            .ToArray();

        Assert.Equal(expectedProjects.Order(StringComparer.Ordinal), projects);
        Assert.Equal(expectedPackages.Order(StringComparer.Ordinal), packages);
    }

    private static string FindRepositoryRoot()
    {
        DirectoryInfo? directory = new(AppContext.BaseDirectory);

        while (directory is not null)
        {
            if (File.Exists(Path.Combine(directory.FullName, "Rendezvous.slnx")))
            {
                return directory.FullName;
            }

            directory = directory.Parent;
        }

        throw new DirectoryNotFoundException("Could not locate the Rendezvous repository root.");
    }

    private static string[] GetReferences(string assemblyName) => Assembly
        .Load(assemblyName)
        .GetReferencedAssemblies()
        .Select(static reference => reference.Name ?? string.Empty)
        .ToArray();

    private static bool IsGodotAssembly(string assemblyName) =>
        assemblyName.StartsWith("Godot", StringComparison.OrdinalIgnoreCase);

    private static bool IsLiteNetLibAssembly(string assemblyName) =>
        string.Equals(assemblyName, "LiteNetLib", StringComparison.Ordinal);

    private static bool IsServerAssembly(string assemblyName) =>
        string.Equals(
            assemblyName,
            "FinalFactory.Rendezvous.Server",
            StringComparison.Ordinal);
}