Add test bitreader test ReadLiteral32BitsWithMsbSet()

tests/ImageSharp.Tests/Formats/Heif/Av1/Av1BitStreamTests.cs

@@ -41,6 +41,32 @@ public class Av1BitStreamTests
         Assert.Equal(expected, actual);
     }
 
+    [Fact]
+    public void ReadLiteral32BitsWithMsbSet()
+    {
+        // arrange
+        // Three 32-bit values with MSB set.
+        byte[] buffer = {
+                          0xff, 0xff, 0xff, 0xff, // 4294967295
+                          0x80, 0xff, 0xee, 0xdd, // 2164256477
+                          0xa0, 0xaa, 0xbb, 0xcc // 2695543756
+                        };
+        uint expected0 = 4294967295;
+        uint expected1 = 2164256477;
+        uint expected2 = 2695543756;
+        Av1BitStreamReader reader = new(buffer);
+
+        // act
+        uint actual0 = reader.ReadLiteral(32);
+        uint actual1 = reader.ReadLiteral(32);
+        uint actual2 = reader.ReadLiteral(32);
+
+        // assert
+        Assert.Equal(expected0, actual0);
+        Assert.Equal(expected1, actual1);
+        Assert.Equal(expected2, actual2);
+    }
+
     [Theory]
     [InlineData(new bool[] { false, false, true, false, true, false, true, false })]
     [InlineData(new bool[] { false, true, false, true })]