Add resolution test

Test Fails just now.


Former-commit-id: da297b15e6ad9c6612378499e7506fade95174d8
Former-commit-id: 9c6106412771f797166983014b7cc976bdae3a3a
Former-commit-id: 394581f30c0ef3e6beb50e32984d8b5315e81710

tests/ImageProcessorCore.Tests/Formats/Jpg/JpegFileTests.cs

@@ -0,0 +1,39 @@
+// <copyright file="SamplerTests.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessorCore.Tests
+{
+    using System.IO;
+
+    using Xunit;
+
+    public class JpegFileTests : FileTestBase
+    {
+        [Fact]
+        public void ResolutionShouldChange()
+        {
+            if (!Directory.Exists("TestOutput/Resolution"))
+            {
+                Directory.CreateDirectory("TestOutput/Resolution");
+            }
+
+            foreach (string file in Files)
+            {
+                using (FileStream stream = File.OpenRead(file))
+                {
+                    string filename = Path.GetFileName(file);
+
+                    Image image = new Image(stream);
+                    using (FileStream output = File.OpenWrite($"TestOutput/Resolution/{filename}"))
+                    {
+                        image.VerticalResolution = 150;
+                        image.HorizontalResolution = 150;
+                        image.Save(output);
+                    }
+                }
+            }
+        }
+    }
+}