Fixes and tests for image format update.

backend/src/Squidex/Areas/Api/Controllers/Assets/AssetContentController.cs

@@ -146,6 +146,7 @@ namespace Squidex.Areas.Api.Controllers.Assets
 
             var contentLength = (long?)null;
             var contentCallback = (FileCallback?)null;
+            var contentType = request.Format?.ToMimeType() ?? asset.MimeType;
 
             if (asset.Type == AssetType.Image && resizeOptions.IsValid)
             {
@@ -183,7 +184,7 @@ namespace Squidex.Areas.Api.Controllers.Assets
                 };
             }
 
-            return new FileCallbackResult(asset.MimeType, contentCallback)
+            return new FileCallbackResult(contentType, contentCallback)
             {
                 EnableRangeProcessing = contentLength > 0,
                 ErrorAs404 = true,

backend/tools/TestSuite/TestSuite.ApiTests/AssetFormatTests.cs

@@ -87,6 +87,25 @@ namespace TestSuite.ApiTests
             await AssertImageAsync(asset);
         }
 
+        [Fact]
+        public async Task Should_upload_image_bmp_and_resize()
+        {
+            var asset = await _.UploadFileAsync("Assets/SampleImage_700kb.bmp", "image/bmp");
+
+            await AssertImageAsync(asset);
+        }
+
+        [Fact]
+        public async Task Should_upload_image_bmp_and_encode_to_webp()
+        {
+            var asset = await _.UploadFileAsync("Assets/SampleImage_700kb.bmp", "image/bmp");
+
+            var (size, type) = await GetReformattedLength(asset.Id, "WEBP");
+
+            Assert.True(size < asset.FileSize);
+            Assert.Equal("image/webp", type);
+        }
+
         private async Task AssertImageAsync(AssetDto asset)
         {
             // Should parse image metadata.
@@ -192,5 +211,24 @@ namespace TestSuite.ApiTests
                 }
             }
         }
+
+        private async Task<(long, string)> GetReformattedLength(string imageId, string format)
+        {
+            var url = $"{_.ClientManager.GenerateImageUrl(imageId)}?format={format}";
+
+            using (var httpClient = _.ClientManager.CreateHttpClient())
+            {
+                var response = await httpClient.GetAsync(url);
+
+                await using (var stream = await response.Content.ReadAsStreamAsync())
+                {
+                    var buffer = new MemoryStream();
+
+                    await stream.CopyToAsync(buffer);
+
+                    return (buffer.Length, response.Content.Headers.ContentType.ToString());
+                }
+            }
+        }
     }
 }