layout: Respect Type and Layout for list template selection

This commit also has some other nice side-effects:

* The layout logic is unified for all page types, which should make it less surprising
* Page.Render now supports all types
* The legacy "indexes" type is removed from the template lookup order. This is an undocumented type from early Hugo days. This means that having a template in, say, `/layouts/indexes/list.html` will no longer work.
* The theme override logic is improved. As an example, an `index.html` in theme will now wn over a `_default/list.html` in the project, which most will expect.

Fixes #3005
Fixes #3245

1 files changed, 46 insertions, 28 deletions

diff --git a/output/layout_test.go b/output/layout_test.go
index 6fb958c9d..3c7fde41a 100644
--- a/output/layout_test.go
+++ b/output/layout_test.go
@@ -14,6 +14,9 @@
 package output
 
 import (
+	"fmt"
+	"reflect"
+	"strings"
 	"testing"
 
 	"github.com/gohugoio/hugo/media"
@@ -37,6 +40,8 @@ func TestLayout(t *testing.T) {
 			BaseName:  "index",
 		}
 
+		htmlFormat = HTMLFormat
+
 		noExtDelimFormat = Format{
 			Name:      "NEM",
 			MediaType: noExtNoDelimMediaType,
@@ -56,57 +61,74 @@ func TestLayout(t *testing.T) {
 		layoutOverride string
 		tp             Format
 		expect         []string
+		expectCount    int
 	}{
 		{"Home", LayoutDescriptor{Kind: "home"}, true, "", ampType,
-			[]string{"index.amp.html", "index.html", "_default/list.amp.html", "_default/list.html", "theme/index.amp.html", "theme/index.html"}},
+			[]string{"index.amp.html", "theme/index.amp.html", "home.amp.html", "theme/home.amp.html", "list.amp.html", "theme/list.amp.html", "index.html", "theme/index.html", "home.html", "theme/home.html", "list.html", "theme/list.html", "_default/index.amp.html"}, 24},
+		{"Home, HTML", LayoutDescriptor{Kind: "home"}, true, "", htmlFormat,
+			// We will eventually get to index.html. This looks stuttery, but makes the lookup logic easy to understand.
+			[]string{"index.html.html", "theme/index.html.html", "home.html.html"}, 24},
 		{"Home, french language", LayoutDescriptor{Kind: "home", Lang: "fr"}, true, "", ampType,
-			[]string{"index.fr.amp.html", "index.amp.html", "index.fr.html", "index.html", "_default/list.fr.amp.html", "_default/list.amp.html", "_default/list.fr.html", "_default/list.html", "theme/index.fr.amp.html", "theme/index.amp.html", "theme/index.fr.html"}},
+			[]string{"index.fr.amp.html", "theme/index.fr.amp.html"},
+			48},
 		{"Home, no ext or delim", LayoutDescriptor{Kind: "home"}, true, "", noExtDelimFormat,
-			[]string{"index.nem", "_default/list.nem"}},
+			[]string{"index.nem", "theme/index.nem", "home.nem", "theme/home.nem", "list.nem"}, 12},
 		{"Home, no ext", LayoutDescriptor{Kind: "home"}, true, "", noExt,
-			[]string{"index.nex", "_default/list.nex"}},
+			[]string{"index.nex", "theme/index.nex", "home.nex", "theme/home.nex", "list.nex"}, 12},
 		{"Page, no ext or delim", LayoutDescriptor{Kind: "page"}, true, "", noExtDelimFormat,
-			[]string{"_default/single.nem", "theme/_default/single.nem"}},
+			[]string{"_default/single.nem", "theme/_default/single.nem"}, 2},
 		{"Section", LayoutDescriptor{Kind: "section", Section: "sect1"}, false, "", ampType,
-			[]string{"section/sect1.amp.html", "section/sect1.html"}},
+			[]string{"sect1/sect1.amp.html", "sect1/section.amp.html", "sect1/list.amp.html", "sect1/sect1.html", "sect1/section.html", "sect1/list.html", "section/sect1.amp.html", "section/section.amp.html"}, 18},
+		{"Section with layout", LayoutDescriptor{Kind: "section", Section: "sect1", Layout: "mylayout"}, false, "", ampType,
+			[]string{"sect1/mylayout.amp.html", "sect1/sect1.amp.html", "sect1/section.amp.html", "sect1/list.amp.html", "sect1/mylayout.html", "sect1/sect1.html"}, 24},
 		{"Taxonomy", LayoutDescriptor{Kind: "taxonomy", Section: "tag"}, false, "", ampType,
-			[]string{"taxonomy/tag.amp.html", "taxonomy/tag.html"}},
+			[]string{"taxonomy/tag.amp.html", "taxonomy/taxonomy.amp.html", "taxonomy/list.amp.html", "taxonomy/tag.html", "taxonomy/taxonomy.html"}, 18},
 		{"Taxonomy term", LayoutDescriptor{Kind: "taxonomyTerm", Section: "categories"}, false, "", ampType,
-			[]string{"taxonomy/categories.terms.amp.html", "taxonomy/categories.terms.html", "_default/terms.amp.html"}},
+			[]string{"taxonomy/categories.terms.amp.html", "taxonomy/terms.amp.html", "taxonomy/list.amp.html", "taxonomy/categories.terms.html", "taxonomy/terms.html"}, 18},
 		{"Page", LayoutDescriptor{Kind: "page"}, true, "", ampType,
-			[]string{"_default/single.amp.html", "_default/single.html", "theme/_default/single.amp.html"}},
+			[]string{"_default/single.amp.html", "theme/_default/single.amp.html", "_default/single.html", "theme/_default/single.html"}, 4},
 		{"Page with layout", LayoutDescriptor{Kind: "page", Layout: "mylayout"}, false, "", ampType,
-			[]string{"_default/mylayout.amp.html", "_default/mylayout.html"}},
+			[]string{"_default/mylayout.amp.html", "_default/single.amp.html", "_default/mylayout.html", "_default/single.html"}, 4},
 		{"Page with layout and type", LayoutDescriptor{Kind: "page", Layout: "mylayout", Type: "myttype"}, false, "", ampType,
-			[]string{"myttype/mylayout.amp.html", "myttype/mylayout.html", "_default/mylayout.amp.html"}},
+			[]string{"myttype/mylayout.amp.html", "myttype/single.amp.html", "myttype/mylayout.html"}, 8},
 		{"Page with layout and type with subtype", LayoutDescriptor{Kind: "page", Layout: "mylayout", Type: "myttype/mysubtype"}, false, "", ampType,
-			[]string{"myttype/mysubtype/mylayout.amp.html", "myttype/mysubtype/mylayout.html", "myttype/mylayout.amp.html"}},
-		{"Page with overridden layout", LayoutDescriptor{Kind: "page", Layout: "mylayout", Type: "myttype"}, false, "myotherlayout", ampType,
-			[]string{"myttype/myotherlayout.amp.html", "myttype/myotherlayout.html"}},
+			[]string{"myttype/mysubtype/mylayout.amp.html", "myttype/mysubtype/single.amp.html", "myttype/mysubtype/mylayout.html"}, 8},
 		// RSS
 		{"RSS Home with theme", LayoutDescriptor{Kind: "home"}, true, "", RSSFormat,
-			[]string{"rss.xml", "_default/rss.xml", "theme/rss.xml", "theme/_default/rss.xml", "_internal/_default/rss.xml"}},
+			[]string{"index.rss.xml", "theme/index.rss.xml", "home.rss.xml", "theme/home.rss.xml", "rss.xml"}, 29},
 		{"RSS Section", LayoutDescriptor{Kind: "section", Section: "sect1"}, false, "", RSSFormat,
-			[]string{"section/sect1.rss.xml", "_default/rss.xml", "rss.xml", "_internal/_default/rss.xml"}},
+			[]string{"sect1/sect1.rss.xml", "sect1/section.rss.xml", "sect1/rss.xml", "sect1/list.rss.xml", "sect1/sect1.xml", "sect1/section.xml"}, 22},
 		{"RSS Taxonomy", LayoutDescriptor{Kind: "taxonomy", Section: "tag"}, false, "", RSSFormat,
-			[]string{"taxonomy/tag.rss.xml", "_default/rss.xml", "rss.xml", "_internal/_default/rss.xml"}},
+			[]string{"taxonomy/tag.rss.xml", "taxonomy/taxonomy.rss.xml", "taxonomy/rss.xml", "taxonomy/list.rss.xml", "taxonomy/tag.xml", "taxonomy/taxonomy.xml"}, 22},
 		{"RSS Taxonomy term", LayoutDescriptor{Kind: "taxonomyTerm", Section: "tag"}, false, "", RSSFormat,
-			[]string{"taxonomy/tag.terms.rss.xml", "_default/rss.xml", "rss.xml", "_internal/_default/rss.xml"}},
+			[]string{"taxonomy/tag.terms.rss.xml", "taxonomy/terms.rss.xml", "taxonomy/rss.xml", "taxonomy/list.rss.xml", "taxonomy/tag.terms.xml"}, 22},
 		{"Home plain text", LayoutDescriptor{Kind: "home"}, true, "", JSONFormat,
-			[]string{"_text/index.json.json", "_text/index.json", "_text/_default/list.json.json", "_text/_default/list.json", "_text/theme/index.json.json", "_text/theme/index.json"}},
+			[]string{"_text/index.json.json", "_text/theme/index.json.json", "_text/home.json.json", "_text/theme/home.json.json"}, 24},
 		{"Page plain text", LayoutDescriptor{Kind: "page"}, true, "", JSONFormat,
-			[]string{"_text/_default/single.json.json", "_text/_default/single.json", "_text/theme/_default/single.json.json"}},
+			[]string{"_text/_default/single.json.json", "_text/theme/_default/single.json.json", "_text/_default/single.json", "_text/theme/_default/single.json"}, 4},
+		{"Reserved section, shortcodes", LayoutDescriptor{Kind: "section", Section: "shortcodes", Type: "shortcodes"}, true, "", ampType,
+			[]string{"section/shortcodes.amp.html", "theme/section/shortcodes.amp.html"}, 24},
+		{"Reserved section, partials", LayoutDescriptor{Kind: "section", Section: "partials", Type: "partials"}, true, "", ampType,
+			[]string{"section/partials.amp.html", "theme/section/partials.amp.html"}, 24},
 	} {
 		t.Run(this.name, func(t *testing.T) {
 			l := NewLayoutHandler(this.hasTheme)
 
-			layouts, err := l.For(this.d, this.layoutOverride, this.tp)
+			layouts, err := l.For(this.d, this.tp)
 
 			require.NoError(t, err)
 			require.NotNil(t, layouts)
-			require.True(t, len(layouts) >= len(this.expect))
+			require.True(t, len(layouts) >= len(this.expect), fmt.Sprint(layouts))
 			// Not checking the complete list for now ...
-			require.Equal(t, this.expect, layouts[:len(this.expect)])
+			got := layouts[:len(this.expect)]
+			if len(layouts) != this.expectCount || !reflect.DeepEqual(got, this.expect) {
+				formatted := strings.Replace(fmt.Sprintf("%v", layouts), "[", "\"", 1)
+				formatted = strings.Replace(formatted, "]", "\"", 1)
+				formatted = strings.Replace(formatted, " ", "\", \"", -1)
+
+				t.Fatalf("Got %d/%d:\n%v\nExpected:\n%v\nAll:\n%v\nFormatted:\n%s", len(layouts), this.expectCount, got, this.expect, layouts, formatted)
+
+			}
 
 			if !this.hasTheme {
 				for _, layout := range layouts {
@@ -116,10 +138,6 @@ func TestLayout(t *testing.T) {
 		})
 	}
 
-	l := NewLayoutHandler(false)
-	_, err := l.For(LayoutDescriptor{Kind: "taxonomyTerm", Section: "tag"}, "override", RSSFormat)
-	require.Error(t, err)
-
 }
 
 func BenchmarkLayout(b *testing.B) {
@@ -127,7 +145,7 @@ func BenchmarkLayout(b *testing.B) {
 	l := NewLayoutHandler(false)
 
 	for i := 0; i < b.N; i++ {
-		layouts, err := l.For(descriptor, "", HTMLFormat)
+		layouts, err := l.For(descriptor, HTMLFormat)
 		require.NoError(b, err)
 		require.NotEmpty(b, layouts)
 	}