Allowed moving local data sources without embedding them again (#1091)

Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/Tests/Tools/PathToolsTests.cs

@@ -0,0 +1,81 @@
+using AIStudio.Tools;
+
+namespace AIStudio.Tests.Tools;
+
+/// <summary>
+/// Checks where a file dialog opens for a file or a folder which was moved or renamed.
+/// </summary>
+/// <remarks>
+/// The native dialog cannot open a place which no longer exists and falls back to wherever it was
+/// used last, which may be anywhere. The nearest folder which still exists is where the file or the
+/// folder was moved from, so its new place is often close by.
+/// </remarks>
+[TestFixture]
+public sealed class PathToolsTests
+{
+    private string testRoot = string.Empty;
+
+    [SetUp]
+    public void CreateTestRoot()
+    {
+        this.testRoot = Path.Combine(Path.GetTempPath(), $"ai-studio-path-tools-{Guid.NewGuid():N}");
+        Directory.CreateDirectory(this.testRoot);
+    }
+
+    [TearDown]
+    public void DeleteTestRoot()
+    {
+        if (Directory.Exists(this.testRoot))
+            Directory.Delete(this.testRoot, true);
+    }
+
+    [Test]
+    public void AnExistingFolderOpensAsItIs()
+    {
+        var folder = Directory.CreateDirectory(Path.Combine(this.testRoot, "documents")).FullName;
+
+        Assert.That(PathTools.FindNearestExistingPath(folder), Is.EqualTo(folder));
+    }
+
+    [Test]
+    public void AnExistingFileOpensAsItIs()
+    {
+        var file = Path.Combine(this.testRoot, "report.pdf");
+        File.WriteAllText(file, "report");
+
+        Assert.That(PathTools.FindNearestExistingPath(file), Is.EqualTo(file));
+    }
+
+    [Test]
+    public void AMovedFolderOpensAtItsNearestFolderWhichStillExists()
+    {
+        var parent = Directory.CreateDirectory(Path.Combine(this.testRoot, "projects")).FullName;
+        var movedFolder = Path.Combine(parent, "2026", "documents");
+
+        Assert.That(PathTools.FindNearestExistingPath(movedFolder), Is.EqualTo(parent), "Every parent folder counts, not only the immediate one.");
+    }
+
+    [Test]
+    public void AMovedFileOpensAtItsFolder()
+    {
+        var file = Path.Combine(this.testRoot, "report.pdf");
+
+        Assert.That(PathTools.FindNearestExistingPath(file), Is.EqualTo(this.testRoot));
+    }
+
+    [TestCase("")]
+    [TestCase("   ")]
+    [TestCase("documents/report.pdf")]
+    public void APathWithoutAPlaceOpensWhereverTheDialogWants(string path)
+    {
+        Assert.That(PathTools.FindNearestExistingPath(path), Is.Null);
+    }
+
+    [Test]
+    public void APathOfAnotherOperatingSystemOpensWhereverTheDialogWants()
+    {
+        var path = OperatingSystem.IsWindows() ? "/Users/somebody/documents" : @"C:\Users\somebody\documents";
+
+        Assert.That(PathTools.FindNearestExistingPath(path), Is.Null, "A backup from another computer must not make the dialog open at a folder which happens to exist here.");
+    }
+}