Fix test.

src/Avalonia.Headless/HeadlessPlatformRenderInterface.cs

@@ -51,7 +51,7 @@ namespace Avalonia.Headless
             return new HeadlessBitmapStub(size, dpi);
         }
 
-        public IWriteableBitmapImpl CreateWriteableBitmap(PixelSize size, Vector dpi, PixelFormat? format = null)
+        public IWriteableBitmapImpl CreateWriteableBitmap(PixelSize size, Vector dpi, PixelFormat? format = null, AlphaFormat? alphaFormat = null)
         {
             return new HeadlessBitmapStub(size, dpi);
         }
@@ -66,7 +66,7 @@ namespace Avalonia.Headless
             return new HeadlessBitmapStub(new Size(1, 1), new Vector(96, 96));
         }
 
-        public IBitmapImpl LoadBitmap(PixelFormat format, IntPtr data, PixelSize size, Vector dpi, int stride)
+        public IBitmapImpl LoadBitmap(PixelFormat format, AlphaFormat alphaFormat, IntPtr data, PixelSize size, Vector dpi, int stride)
         {
             return new HeadlessBitmapStub(new Size(1, 1), new Vector(96, 96));
         }        

tests/Avalonia.Benchmarks/NullRenderingPlatform.cs

@@ -46,7 +46,7 @@ namespace Avalonia.Benchmarks
             throw new NotImplementedException();
         }
 
-        public IWriteableBitmapImpl CreateWriteableBitmap(PixelSize size, Vector dpi, PixelFormat? format = null)
+        public IWriteableBitmapImpl CreateWriteableBitmap(PixelSize size, Vector dpi, PixelFormat? format = null, AlphaFormat? alphaFormat = null)
         {
             throw new NotImplementedException();
         }
@@ -61,7 +61,7 @@ namespace Avalonia.Benchmarks
             throw new NotImplementedException();
         }
 
-        public IBitmapImpl LoadBitmap(PixelFormat format, IntPtr data, PixelSize size, Vector dpi, int stride)
+        public IBitmapImpl LoadBitmap(PixelFormat format, AlphaFormat alphaFormat, IntPtr data, PixelSize size, Vector dpi, int stride)
         {
             throw new NotImplementedException();
         }

tests/Avalonia.RenderTests/Media/BitmapTests.cs

@@ -81,7 +81,7 @@ namespace Avalonia.Direct2D1.RenderTests.Media
                 ctx.PopOpacity();
             }
 
-            var bmp = new Bitmap(fmt, fb.Address, fb.Size, new Vector(96, 96), fb.RowBytes);
+            var bmp = new Bitmap(fmt, AlphaFormat.Premul, fb.Address, fb.Size, new Vector(96, 96), fb.RowBytes);
             fb.Deallocate();
             using (var rtb = new RenderTargetBitmap(new PixelSize(100, 100), new Vector(96, 96)))
             {

tests/Avalonia.UnitTests/MockPlatformRenderInterface.cs

@@ -55,7 +55,8 @@ namespace Avalonia.UnitTests
         public IWriteableBitmapImpl CreateWriteableBitmap(
             PixelSize size,
             Vector dpi,
-            PixelFormat? format = default(PixelFormat?))
+            PixelFormat? format = null,
+            AlphaFormat? alphaFormat = null)
         {
             throw new NotImplementedException();
         }
@@ -87,6 +88,7 @@ namespace Avalonia.UnitTests
 
         public IBitmapImpl LoadBitmap(
             PixelFormat format,
+            AlphaFormat alphaFormat,
             IntPtr data,
             PixelSize size,
             Vector dpi,

tests/Avalonia.Visuals.UnitTests/VisualTree/MockRenderInterface.cs

@@ -47,7 +47,7 @@ namespace Avalonia.Visuals.UnitTests.VisualTree
             throw new NotImplementedException();
         }
 
-        public IBitmapImpl LoadBitmap(PixelFormat format, IntPtr data, PixelSize size, Vector dpi, int stride)
+        public IBitmapImpl LoadBitmap(PixelFormat format, AlphaFormat alphaFormat, IntPtr data, PixelSize size, Vector dpi, int stride)
         {
             throw new NotImplementedException();
         }
@@ -64,7 +64,7 @@ namespace Avalonia.Visuals.UnitTests.VisualTree
             return new MockFontManagerImpl();
         }
 
-        public IWriteableBitmapImpl CreateWriteableBitmap(PixelSize size, Vector dpi, PixelFormat? fmt)
+        public IWriteableBitmapImpl CreateWriteableBitmap(PixelSize size, Vector dpi, PixelFormat? fmt, AlphaFormat? alphaFormat)
         {
             throw new NotImplementedException();
         }