Fix MediaType when reading images from cache

Fixes #8931

resources/integration_test.go

@@ -0,0 +1,69 @@
+// Copyright 2022 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resources_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/gohugoio/hugo/hugolib"
+)
+
+// Issue 8931
+func TestImageCache(t *testing.T) {
+
+	files := `
+-- config.toml --
+baseURL = "https://example.org"
+-- content/mybundle/index.md --
+---
+title: "My Bundle"
+---
+-- content/mybundle/pixel.png --
+iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNkYPhfDwAChwGA60e6kgAAAABJRU5ErkJggg==
+-- layouts/foo.html --
+-- layouts/index.html --
+{{ $p := site.GetPage "mybundle"}}
+{{ $img := $p.Resources.Get "pixel.png" }}
+{{ $gif := $img.Resize "1x1 gif" }}
+{{ $bmp := $img.Resize "1x1 bmp" }}
+
+gif: {{ $gif.RelPermalink }}|{{ $gif.MediaType }}|
+bmp: {{ $bmp.RelPermalink }}|{{ $bmp.MediaType }}|	
+`
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+			NeedsOsFS:   true,
+			Running:     true,
+		}).Build()
+
+	assertImages := func() {
+		b.AssertFileContent("public/index.html", `
+		gif: /mybundle/pixel_hu8aa3346827e49d756ff4e630147c42b5_70_1x1_resize_box_3.gif|image/gif|
+		bmp: /mybundle/pixel_hu8aa3346827e49d756ff4e630147c42b5_70_1x1_resize_box_3.bmp|image/bmp|
+		
+		`)
+	}
+
+	assertImages()
+
+	b.EditFileReplace("content/mybundle/index.md", func(s string) string { return strings.ReplaceAll(s, "Bundle", "BUNDLE") })
+	b.Build()
+
+	assertImages()
+
+}