Adds ImageExtensionsTest for png.

tests/ImageSharp.Tests/Formats/Png/ImageExtensionsTest.cs

@@ -0,0 +1,152 @@
+using System.IO;
+using System.Threading.Tasks;
+using SixLabors.ImageSharp.Formats;
+using SixLabors.ImageSharp.Formats.Png;
+using SixLabors.ImageSharp.PixelFormats;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests.Formats.Png
+{
+    public class ImageExtensionsTest
+    {
+        [Fact]
+        public void SaveAsPng_Path()
+        {
+            string dir = TestEnvironment.CreateOutputDirectory(nameof(ImageExtensionsTest));
+            string file = Path.Combine(dir, "SaveAsPng_Path.png");
+
+            using (var image = new Image<Rgba32>(10, 10))
+            {
+                image.SaveAsPng(file);
+            }
+
+            using (Image.Load(file, out IImageFormat mime))
+            {
+                Assert.Equal("image/png", mime.DefaultMimeType);
+            }
+        }
+
+        [Fact]
+        public async Task SaveAsPngAsync_Path()
+        {
+            string dir = TestEnvironment.CreateOutputDirectory(nameof(ImageExtensionsTest));
+            string file = Path.Combine(dir, "SaveAsPngAsync_Path.png");
+
+            using (var image = new Image<Rgba32>(10, 10))
+            {
+                await image.SaveAsPngAsync(file);
+            }
+
+            using (Image.Load(file, out IImageFormat mime))
+            {
+                Assert.Equal("image/png", mime.DefaultMimeType);
+            }
+        }
+
+        [Fact]
+        public void SaveAsPng_Path_Encoder()
+        {
+            string dir = TestEnvironment.CreateOutputDirectory(nameof(ImageExtensions));
+            string file = Path.Combine(dir, "SaveAsPng_Path_Encoder.png");
+
+            using (var image = new Image<Rgba32>(10, 10))
+            {
+                image.SaveAsPng(file, new PngEncoder());
+            }
+
+            using (Image.Load(file, out IImageFormat mime))
+            {
+                Assert.Equal("image/png", mime.DefaultMimeType);
+            }
+        }
+
+        [Fact]
+        public async Task SaveAsPngAsync_Path_Encoder()
+        {
+            string dir = TestEnvironment.CreateOutputDirectory(nameof(ImageExtensions));
+            string file = Path.Combine(dir, "SaveAsPngAsync_Path_Encoder.png");
+
+            using (var image = new Image<Rgba32>(10, 10))
+            {
+                await image.SaveAsPngAsync(file, new PngEncoder());
+            }
+
+            using (Image.Load(file, out IImageFormat mime))
+            {
+                Assert.Equal("image/png", mime.DefaultMimeType);
+            }
+        }
+
+        [Fact]
+        public void SaveAsPng_Stream()
+        {
+            using var memoryStream = new MemoryStream();
+
+            using (var image = new Image<Rgba32>(10, 10))
+            {
+                image.SaveAsPng(memoryStream);
+            }
+
+            memoryStream.Position = 0;
+
+            using (Image.Load(memoryStream, out IImageFormat mime))
+            {
+                Assert.Equal("image/png", mime.DefaultMimeType);
+            }
+        }
+
+        [Fact]
+        public async Task SaveAsPngAsync_StreamAsync()
+        {
+            using var memoryStream = new MemoryStream();
+
+            using (var image = new Image<Rgba32>(10, 10))
+            {
+                await image.SaveAsPngAsync(memoryStream);
+            }
+
+            memoryStream.Position = 0;
+
+            using (Image.Load(memoryStream, out IImageFormat mime))
+            {
+                Assert.Equal("image/png", mime.DefaultMimeType);
+            }
+        }
+
+        [Fact]
+        public void SaveAsPng_Stream_Encoder()
+        {
+            using var memoryStream = new MemoryStream();
+
+            using (var image = new Image<Rgba32>(10, 10))
+            {
+                image.SaveAsPng(memoryStream, new PngEncoder());
+            }
+
+            memoryStream.Position = 0;
+
+            using (Image.Load(memoryStream, out IImageFormat mime))
+            {
+                Assert.Equal("image/png", mime.DefaultMimeType);
+            }
+        }
+
+        [Fact]
+        public async Task SaveAsPngAsync_Stream_Encoder()
+        {
+            using var memoryStream = new MemoryStream();
+
+            using (var image = new Image<Rgba32>(10, 10))
+            {
+                await image.SaveAsPngAsync(memoryStream, new PngEncoder());
+            }
+
+            memoryStream.Position = 0;
+
+            using (Image.Load(memoryStream, out IImageFormat mime))
+            {
+                Assert.Equal("image/png", mime.DefaultMimeType);
+            }
+        }
+    }
+}