Image resource refactor

This commit pulls most of the image related logic into its own package, to make it easier to reason about and extend.

This is also a rewrite of the transformation logic used in Hugo Pipes, mostly to allow constructs like the one below:

    {{ ($myimg | fingerprint ).Width }}

Fixes #5903
Fixes #6234
Fixes #6266

hugolib/pagebundler_test.go

@@ -42,8 +42,7 @@ import (
 )
 
 func TestPageBundlerSiteRegular(t *testing.T) {
-	t.Parallel()
-
+	c := qt.New(t)
 	baseBaseURL := "https://example.com"
 
 	for _, baseURLPath := range []string{"", "/hugo"} {
@@ -55,15 +54,14 @@ func TestPageBundlerSiteRegular(t *testing.T) {
 				}
 				ugly := ugly
 				canonify := canonify
-				t.Run(fmt.Sprintf("ugly=%t,canonify=%t,path=%s", ugly, canonify, baseURLPathId),
-					func(t *testing.T) {
-						t.Parallel()
+				c.Run(fmt.Sprintf("ugly=%t,canonify=%t,path=%s", ugly, canonify, baseURLPathId),
+					func(c *qt.C) {
+						c.Parallel()
 						baseURL := baseBaseURL + baseURLPath
 						relURLBase := baseURLPath
 						if canonify {
 							relURLBase = ""
 						}
-						c := qt.New(t)
 						fs, cfg := newTestBundleSources(t)
 						cfg.Set("baseURL", baseURL)
 						cfg.Set("canonifyURLs", canonify)

hugolib/resource_chain_test.go

@@ -14,6 +14,7 @@
 package hugolib
 
 import (
+	"io"
 	"os"
 	"path/filepath"
 	"testing"
@@ -167,6 +168,64 @@ T1: {{ $r.Content }}
 
 }
 
+func TestResourceChainBasic(t *testing.T) {
+	t.Parallel()
+
+	b := newTestSitesBuilder(t)
+	b.WithTemplatesAdded("index.html", `
+{{ $hello := "<h1>     Hello World!   </h1>" | resources.FromString "hello.html" | fingerprint "sha512" | minify  | fingerprint }}
+
+HELLO: {{ $hello.Name }}|{{ $hello.RelPermalink }}|{{ $hello.Content | safeHTML }}
+
+{{ $img := resources.Get "images/sunset.jpg" }}
+{{ $fit := $img.Fit "200x200" }}
+{{ $fit2 := $fit.Fit "100x200" }}
+{{ $img = $img | fingerprint }}
+SUNSET: {{ $img.Name }}|{{ $img.RelPermalink }}|{{ $img.Width }}|{{ len $img.Content }}
+FIT: {{ $fit.Name }}|{{ $fit.RelPermalink }}|{{ $fit.Width }}
+`)
+
+	fs := b.Fs.Source
+
+	imageDir := filepath.Join("assets", "images")
+	b.Assert(os.MkdirAll(imageDir, 0777), qt.IsNil)
+	src, err := os.Open("testdata/sunset.jpg")
+	b.Assert(err, qt.IsNil)
+	out, err := fs.Create(filepath.Join(imageDir, "sunset.jpg"))
+	b.Assert(err, qt.IsNil)
+	_, err = io.Copy(out, src)
+	b.Assert(err, qt.IsNil)
+	out.Close()
+
+	b.Running()
+
+	for i := 0; i < 2; i++ {
+
+		b.Build(BuildCfg{})
+
+		b.AssertFileContent("public/index.html",
+			`
+SUNSET: images/sunset.jpg|/images/sunset.a9bf1d944e19c0f382e0d8f51de690f7d0bc8fa97390c4242a86c3e5c0737e71.jpg|900|90587
+FIT: images/sunset.jpg|/images/sunset_hu59e56ffff1bc1d8d122b1403d34e039f_90587_200x200_fit_q75_box.jpg|200
+
+`)
+
+		b.EditFiles("page1.md", `
+---
+title: "Page 1 edit"
+summary: "Edited summary"
+---
+
+Edited content.
+
+`)
+
+		b.Assert(b.Fs.Destination.Remove("public"), qt.IsNil)
+		b.H.ResourceSpec.ClearCaches()
+
+	}
+}
+
 func TestResourceChain(t *testing.T) {
 	t.Parallel()
 
@@ -353,9 +412,11 @@ Publish 2: {{ $cssPublish2.Permalink }}
 				"Publish 1: body{color:blue} /external1.min.css",
 				"Publish 2: http://example.com/external2.min.css",
 			)
-			c.Assert(b.CheckExists("public/external2.min.css"), qt.Equals, true)
-			c.Assert(b.CheckExists("public/external1.min.css"), qt.Equals, true)
-			c.Assert(b.CheckExists("public/inline.min.css"), qt.Equals, false)
+			b.Assert(b.CheckExists("public/external2.css"), qt.Equals, false)
+			b.Assert(b.CheckExists("public/external1.css"), qt.Equals, false)
+			b.Assert(b.CheckExists("public/external2.min.css"), qt.Equals, true)
+			b.Assert(b.CheckExists("public/external1.min.css"), qt.Equals, true)
+			b.Assert(b.CheckExists("public/inline.min.css"), qt.Equals, false)
 		}},
 
 		{"unmarshal", func() bool { return true }, func(b *sitesBuilder) {

hugolib/testhelpers_test.go

@@ -536,6 +536,7 @@ func (s *sitesBuilder) changeEvents() []fsnotify.Event {
 }
 
 func (s *sitesBuilder) build(cfg BuildCfg, shouldFail bool) *sitesBuilder {
+	s.Helper()
 	defer func() {
 		s.changedFiles = nil
 	}()