Add RepositoryResolverFactory and revert behaviour change with no sea…

…rch path

src/Generation/GirLoader/Helper/NullRepositoryResolver.cs

@@ -0,0 +1,9 @@
+namespace GirLoader;
+
+public class NullRepositoryResolver : IRepositoryResolver
+{
+    public Input.Repository? ResolveRepository(string fileName)
+    {
+        return null;
+    }
+}

src/Generation/GirLoader/Helper/RepositoryResolverFactory.cs

@@ -0,0 +1,39 @@
+using System.Reflection;
+
+namespace GirLoader;
+
+public class RepositoryResolverFactory
+{
+    private readonly string _platform;
+    private readonly string? _platformSearchPath;
+    private readonly Assembly _assembly;
+
+    /// <summary>
+    /// Construct a new RepositoryResolverFactory
+    /// </summary>
+    /// <param name="platform">The platform to resolve repositories for</param>
+    /// <param name="platformSearchPath">Directory containing repository files for this platform.
+    /// If null, no repositories will be resolved for this platform.</param>
+    /// <param name="assembly">Assembly containing embedded repository files.
+    /// These are used as a fallback if no repository file is found in the search path.</param>
+    public RepositoryResolverFactory(string platform, string? platformSearchPath, Assembly assembly)
+    {
+        _platform = platform;
+        _platformSearchPath = platformSearchPath;
+        _assembly = assembly;
+    }
+
+    public IRepositoryResolver Create()
+    {
+        if (_platformSearchPath == null)
+        {
+            return new NullRepositoryResolver();
+        }
+
+        var directoryResolver = new DirectoryRepositoryResolver(_platformSearchPath);
+        var embeddedResolver = new EmbeddedRepositoryResolver(_assembly, _platform);
+
+        return new ChainedRepositoryResolver(
+            new IRepositoryResolver[] { directoryResolver, embeddedResolver });
+    }
+}

src/Generation/GirTool/GenerateCommand.cs

@@ -139,7 +139,8 @@ private static (DeserializedInput, DeserializedInput, DeserializedInput) LoadRep
 
     private static DeserializedInput DeserializeInput(string platformName, string? searchPath, string[] input)
     {
-        var repositoryResolver = GetRepositoryResolver(platformName, searchPath);
+        var repositoryResolver = new RepositoryResolverFactory(
+            platformName, searchPath, typeof(GenerateCommand).Assembly).Create();
 
         var inputRepositories = input
             .Select(fileName => repositoryResolver.ResolveRepository(fileName))
@@ -159,23 +160,6 @@ private static DeserializedInput DeserializeInput(string platformName, string? s
         return new DeserializedInput(outputRepositories, inputNamespaces);
     }
 
-    private static IRepositoryResolver GetRepositoryResolver(string platformName, string? searchPath)
-    {
-        var assembly = typeof(GenerateCommand).Assembly;
-        var embeddedResolver = new EmbeddedRepositoryResolver(assembly, platformName);
-
-        if (searchPath == null)
-        {
-            return embeddedResolver;
-        }
-        else
-        {
-            var directoryResolver = new DirectoryRepositoryResolver(searchPath);
-            return new ChainedRepositoryResolver(
-                new IRepositoryResolver[] { directoryResolver, embeddedResolver });
-        }
-    }
-
     private static string GetNamespaceName(GirModel.Namespace ns)
     {
         return $"{ns.Name}-{ns.Version}";

src/Tests/Generation/GirLoader.Tests/RepositoryResolverFactoryTests.cs

@@ -0,0 +1,49 @@
+using System.IO;
+using FluentAssertions;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace GirLoader.Test;
+
+[TestClass, TestCategory("UnitTest")]
+public class RepositoryResolverFactoryTests
+{
+    [TestMethod]
+    public void RepositoriesNotResolvedWithNullSearchPath()
+    {
+        var assembly = typeof(RepositoryResolverFactoryTests).Assembly;
+        var factory = new RepositoryResolverFactory("linux", null, assembly);
+
+        var resolver = factory.Create();
+        var repository = resolver.ResolveRepository("GObject-2.0.gir");
+
+        repository.Should().BeNull();
+    }
+
+    [TestMethod]
+    public void RepositoriesResolvedFromSearchPath()
+    {
+        using var directory = new DisposableTempDirectory();
+        var filePath = Path.Join(directory.Path, "NewLibrary-1.0.gir");
+        File.WriteAllText(filePath, InputRepositoryHelper.CreateXml("NewLibrary", "1.0"));
+        var assembly = typeof(RepositoryResolverFactoryTests).Assembly;
+        var factory = new RepositoryResolverFactory("linux", directory.Path, assembly);
+
+        var resolver = factory.Create();
+        var repository = resolver.ResolveRepository("NewLibrary-1.0.gir");
+
+        repository!.Namespace!.Name.Should().Be("NewLibrary");
+    }
+
+    [TestMethod]
+    public void RepositoriesResolvedFromEmbeddedFilesWhenSearchPathSet()
+    {
+        using var directory = new DisposableTempDirectory();
+        var assembly = typeof(RepositoryResolverFactoryTests).Assembly;
+        var factory = new RepositoryResolverFactory("linux", directory.Path, assembly);
+
+        var resolver = factory.Create();
+        var repository = resolver.ResolveRepository("GObject-2.0.gir");
+
+        repository!.Namespace!.Name.Should().Be("GObject");
+    }
+}