content adapter: Handle <!--more--> separator in content.value

Closes gohugoio#12556

hugolib/pagesfromdata/pagesfromgotmpl_integration_test.go

@@ -643,3 +643,29 @@ Footer: {{ range index site.Menus.footer }}{{ .Name }}|{{ end }}|
 		"Footer: Footer|p2||",
 	)
 }
+
+func TestPagesFromGoTmplMore(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- hugo.toml --
+disableKinds = ['home','rss','section','sitemap','taxonomy','term']
+[markup.goldmark.renderer]
+unsafe = true
+-- content/s1/_content.gotmpl --
+{{ $page := dict
+	"content" (dict "mediaType" "text/markdown" "value" "aaa <!--more--> bbb")
+	"title" "p1"
+	"path" "p1"
+  }}
+  {{ .AddPage $page }}
+-- layouts/_default/single.html --
+summary: {{ .Summary }}|content: {{ .Content}}
+`
+
+	b := hugolib.Test(t, files)
+
+	b.AssertFileContent("public/s1/p1/index.html",
+		"<p>aaa</p>|content: <p>aaa</p>\n<p>bbb</p>",
+	)
+}

parser/pageparser/pagelexer.go

@@ -70,9 +70,10 @@ type Config struct {
 // can be set if position of first shortcode is known
 func newPageLexer(input []byte, stateStart stateFunc, cfg Config) *pageLexer {
 	lexer := &pageLexer{
-		input:      input,
-		stateStart: stateStart,
-		cfg:        cfg,
+		input:          input,
+		stateStart:     stateStart,
+		summaryDivider: summaryDivider,
+		cfg:            cfg,
 		lexerShortcodeState: lexerShortcodeState{
 			currLeftDelimItem:  tLeftDelimScNoMarkup,
 			currRightDelimItem: tRightDelimScNoMarkup,

parser/pageparser/pagelexer_intro.go

@@ -14,8 +14,6 @@
 package pageparser
 
 func lexIntroSection(l *pageLexer) stateFunc {
-	l.summaryDivider = summaryDivider
-
 LOOP:
 	for {
 		r := l.next()

parser/pageparser/pageparser_test.go

@@ -101,3 +101,14 @@ func BenchmarkHasShortcode(b *testing.B) {
 		}
 	})
 }
+
+func TestSummaryDividerStartingFromMain(t *testing.T) {
+	c := qt.New(t)
+
+	input := `aaa <!--more--> bbb`
+	items, err := collectStringMain(input)
+	c.Assert(err, qt.IsNil)
+
+	c.Assert(items, qt.HasLen, 4)
+	c.Assert(items[1].Type, qt.Equals, TypeLeadSummaryDivider)
+}