Add TestFixtures.Resources project for manual resource-view tests

Single .NET classlib that embeds one resource of every type the Avalonia port
recognises — .xml / .xsd / .xslt / .xaml / .png / .bmp / .jpg / .gif / .ico /
.cur / .resources / .bin (unknown-extension fall-through). The image fixtures
render a 64×64 cream square with a blue circle and red diagonal stripe so the
inline preview is obviously decoded rather than blank; the .ico is multi-frame
(16/32/48) so future per-frame work has something to chew on.

Assisted-by: Claude:claude-opus-4-7:Claude Code

TestFixtures.Resources/Generate.cs

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+// Tiny helper that produces all the binary fixture files (PNG / BMP / JPG / GIF / ICO / CUR /
+// .resources / .bin) into the fixtures/ directory. Text fixtures (XML / XSD / XSLT / XAML) are
+// checked in as-is. Run with `dotnet run --project Generate.csproj` from this directory.
+//
+// Each image format renders an obvious recognizable shape (coloured square with a circle and a
+// diagonal stripe) at 64×64 so manual ILSpy testing can eyeball that the rendering pipeline
+// is decoding the bytes — not just rendering a blank tile.
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Resources;
+
+using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.Drawing.Processing;
+using SixLabors.ImageSharp.Formats;
+using SixLabors.ImageSharp.Formats.Bmp;
+using SixLabors.ImageSharp.Formats.Gif;
+using SixLabors.ImageSharp.Formats.Jpeg;
+using SixLabors.ImageSharp.Formats.Png;
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing;
+
+var dir = Path.Combine(AppContext.BaseDirectory, "..", "..", "..", "fixtures");
+dir = Path.GetFullPath(dir);
+Directory.CreateDirectory(dir);
+
+WriteImage(Path.Combine(dir, "logo.png"), new PngEncoder());
+WriteImage(Path.Combine(dir, "logo.bmp"), new BmpEncoder());
+WriteImage(Path.Combine(dir, "logo.jpg"), new JpegEncoder { Quality = 92 });
+WriteImage(Path.Combine(dir, "logo.gif"), new GifEncoder());
+
+// Multi-frame .ico: 16x16, 32x32, 48x48, each PNG-encoded inside the ICO container so Avalonia
+// can decode the largest frame for preview while a savvy viewer can pick any.
+File.WriteAllBytes(Path.Combine(dir, "favicon.ico"), BuildIcoOrCur(isCursor: false, sizes: new[] { 16, 32, 48 }));
+File.WriteAllBytes(Path.Combine(dir, "pointer.cur"), BuildIcoOrCur(isCursor: true, sizes: new[] { 32 }));
+
+// .resources file with a mix of strings and other-typed entries — the .resources DataGrid view
+// splits these into two tables.
+var ms = new MemoryStream();
+using (var rw = new ResourceWriter(ms))
+{
+    rw.AddResource("greeting", "Hello, world");
+    rw.AddResource("city", "Linz");
+    rw.AddResource("year", 2026);
+    rw.AddResource("ratio", 1.61803);
+    rw.AddResource("flag", true);
+}
+File.WriteAllBytes(Path.Combine(dir, "Strings.resources"), ms.ToArray());
+
+// Unknown extension — should fall through to the generic ResourceTreeNode.
+File.WriteAllBytes(Path.Combine(dir, "blob.bin"), new byte[] { 0xDE, 0xAD, 0xBE, 0xEF, 0xCA, 0xFE, 0xBA, 0xBE });
+
+Console.WriteLine($"Wrote fixtures into {dir}");
+
+// --- helpers ---
+
+static void WriteImage(string path, IImageEncoder encoder, int size = 64)
+{
+    using var img = RenderShape(size);
+    using var fs = File.Create(path);
+    img.Save(fs, encoder);
+}
+
+static Image<Rgba32> RenderShape(int size)
+{
+    var img = new Image<Rgba32>(size, size, new Rgba32(0xFF, 0xF6, 0xE5));
+    img.Mutate(ctx => {
+        // Filled blue circle in the centre.
+        ctx.Fill(new Rgba32(0x33, 0x99, 0xCC),
+            new SixLabors.ImageSharp.Drawing.EllipsePolygon(size / 2f, size / 2f, size * 0.35f));
+        // Red diagonal stripe.
+        ctx.DrawLine(new Rgba32(0xCC, 0x33, 0x33),
+            Math.Max(2, size / 16f),
+            new PointF(0, size),
+            new PointF(size, 0));
+        // 1px dark border so the bounds are obvious against any background.
+        ctx.Draw(new Rgba32(0x33, 0x33, 0x33), 1,
+            new RectangleF(0, 0, size - 1, size - 1));
+    });
+    return img;
+}
+
+// Builds an ICO/CUR file containing one PNG-encoded entry per requested size. The on-disk
+// layout: ICONDIR + ICONDIRENTRY[*] + concatenated frame bytes; only byte 2 (image type)
+// distinguishes ICO (1) from CUR (2). Hotspot for cursors is centred at (size/2, size/2).
+static byte[] BuildIcoOrCur(bool isCursor, int[] sizes)
+{
+    var frames = new List<byte[]>(sizes.Length);
+    var pngEncoder = new PngEncoder();
+    foreach (var sz in sizes)
+    {
+        using var img = RenderShape(sz);
+        using var ms = new MemoryStream();
+        img.Save(ms, pngEncoder);
+        frames.Add(ms.ToArray());
+    }
+    var fileMs = new MemoryStream();
+    var w = new BinaryWriter(fileMs);
+    w.Write((ushort)0);                                                  // reserved
+    w.Write((ushort)(isCursor ? 2 : 1));                                 // type: 1=ICO, 2=CUR
+    w.Write((ushort)sizes.Length);                                       // image count
+    int dirSize = 6 + 16 * sizes.Length;
+    int offset = dirSize;
+    for (int i = 0; i < sizes.Length; i++)
+    {
+        var sz = sizes[i];
+        var dim = (byte)(sz >= 256 ? 0 : sz);
+        w.Write(dim);                                                    // width
+        w.Write(dim);                                                    // height
+        w.Write((byte)0);                                                // palette count
+        w.Write((byte)0);                                                // reserved
+        if (isCursor)
+        {
+            w.Write((ushort)(sz / 2));                                   // hotspot X
+            w.Write((ushort)(sz / 2));                                   // hotspot Y
+        }
+        else
+        {
+            w.Write((ushort)1);                                          // colour planes
+            w.Write((ushort)32);                                         // bits per pixel
+        }
+        w.Write((uint)frames[i].Length);                                 // bytes in frame
+        w.Write((uint)offset);                                           // offset to frame
+        offset += frames[i].Length;
+    }
+    foreach (var frame in frames)
+        w.Write(frame);
+    return fileMs.ToArray();
+}

TestFixtures.Resources/Generate.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <RootNamespace>TestFixtures.Generate</RootNamespace>
+    <Nullable>enable</Nullable>
+    <!-- This generator runs once to (re)build the binary fixtures and isn't part of the
+         solution's CPM scope; pin SkiaSharp inline so the parent Directory.Packages.props
+         doesn't need to learn about a one-shot tool. -->
+    <ManagePackageVersionsCentrally>false</ManagePackageVersionsCentrally>
+  </PropertyGroup>
+  <ItemGroup>
+    <!-- ImageSharp covers every encoder we need (PNG/JPG/BMP/GIF) cross-platform; SkiaSharp's
+         encoder list doesn't include BMP/GIF. -->
+    <PackageReference Include="SixLabors.ImageSharp" Version="3.1.11" />
+    <PackageReference Include="SixLabors.ImageSharp.Drawing" Version="2.1.4" />
+  </ItemGroup>
+</Project>

TestFixtures.Resources/TestFixtures.Resources.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <AssemblyName>TestFixtures.Resources</AssemblyName>
+    <RootNamespace>TestFixtures.Resources</RootNamespace>
+    <Nullable>enable</Nullable>
+    <!-- Standalone fixture for manual ILSpy testing — keep build artifacts entirely
+         under this directory so the parent solution doesn't try to compile it. -->
+    <BaseOutputPath>$(MSBuildThisFileDirectory)bin\</BaseOutputPath>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <!-- Each resource keeps its file name as the manifest name so it ends up routed to the
+         right specialised resource node by extension. -->
+    <EmbeddedResource Include="fixtures\sample.xml"     LogicalName="sample.xml" />
+    <EmbeddedResource Include="fixtures\schema.xsd"     LogicalName="schema.xsd" />
+    <EmbeddedResource Include="fixtures\transform.xslt" LogicalName="transform.xslt" />
+    <EmbeddedResource Include="fixtures\Window.xaml"    LogicalName="Window.xaml" />
+    <EmbeddedResource Include="fixtures\logo.png"       LogicalName="logo.png" />
+    <EmbeddedResource Include="fixtures\logo.bmp"       LogicalName="logo.bmp" />
+    <EmbeddedResource Include="fixtures\logo.jpg"       LogicalName="logo.jpg" />
+    <EmbeddedResource Include="fixtures\logo.gif"       LogicalName="logo.gif" />
+    <EmbeddedResource Include="fixtures\favicon.ico"    LogicalName="favicon.ico" />
+    <EmbeddedResource Include="fixtures\pointer.cur"    LogicalName="pointer.cur" />
+    <EmbeddedResource Include="fixtures\Strings.resources" LogicalName="Strings.resources" />
+    <EmbeddedResource Include="fixtures\blob.bin"       LogicalName="blob.bin" />
+  </ItemGroup>
+
+  <!-- Generate.cs is for the Generate.csproj only; exclude from compilation here. -->
+  <ItemGroup>
+    <Compile Remove="Generate.cs" />
+    <None Remove="Generate.cs" />
+  </ItemGroup>
+</Project>

TestFixtures.Resources/fixtures/Window.xaml

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+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        Title="Demo Window"
+        Width="640"
+        Height="480">
+  <DockPanel>
+    <TextBlock DockPanel.Dock="Top"
+               Text="Hello, world"
+               FontSize="20"
+               Margin="12" />
+    <Border BorderBrush="Gray"
+            BorderThickness="1"
+            Margin="12">
+      <StackPanel>
+        <Button Content="Click me" />
+        <TextBox Text="Some text" />
+      </StackPanel>
+    </Border>
+  </DockPanel>
+</Window>

TestFixtures.Resources/fixtures/blob.bin

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+ﾞｭｾ<EFBFBD><EFBFBD>ｺｾ

TestFixtures.Resources/fixtures/sample.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+  <appSettings>
+    <add key="environment" value="staging" />
+    <add key="timeoutSeconds" value="30" />
+  </appSettings>
+  <connectionStrings>
+    <add name="default"
+         connectionString="Data Source=.;Initial Catalog=Demo;Integrated Security=True"
+         providerName="System.Data.SqlClient" />
+  </connectionStrings>
+  <runtime>
+    <gcServer enabled="true" />
+  </runtime>
+</configuration>

TestFixtures.Resources/fixtures/schema.xsd

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+<?xml version="1.0" encoding="utf-8"?>
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
+           targetNamespace="http://example.com/order"
+           xmlns="http://example.com/order"
+           elementFormDefault="qualified">
+  <xs:element name="order">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element name="customer" type="xs:string" />
+        <xs:element name="items">
+          <xs:complexType>
+            <xs:sequence>
+              <xs:element name="item" maxOccurs="unbounded">
+                <xs:complexType>
+                  <xs:attribute name="sku" type="xs:string" use="required" />
+                  <xs:attribute name="qty" type="xs:positiveInteger" use="required" />
+                </xs:complexType>
+              </xs:element>
+            </xs:sequence>
+          </xs:complexType>
+        </xs:element>
+      </xs:sequence>
+      <xs:attribute name="id" type="xs:string" use="required" />
+    </xs:complexType>
+  </xs:element>
+</xs:schema>

TestFixtures.Resources/fixtures/transform.xslt

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+<?xml version="1.0" encoding="utf-8"?>
+<xsl:stylesheet version="1.0"
+                xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
+  <xsl:output method="html" indent="yes" />
+
+  <xsl:template match="/orders">
+    <html>
+      <body>
+        <h1>Orders</h1>
+        <table border="1">
+          <tr>
+            <th>ID</th>
+            <th>Customer</th>
+          </tr>
+          <xsl:for-each select="order">
+            <tr>
+              <td><xsl:value-of select="@id" /></td>
+              <td><xsl:value-of select="customer" /></td>
+            </tr>
+          </xsl:for-each>
+        </table>
+      </body>
+    </html>
+  </xsl:template>
+</xsl:stylesheet>