Localize all the GroupBy*Date methods

Fixes #9745

6 files changed, 116 insertions, 29 deletions

diff --git a/resources/page/integration_test.go b/resources/page/integration_test.go
new file mode 100644
index 000000000..285b14342
--- /dev/null
+++ b/resources/page/integration_test.go
@@ -0,0 +1,72 @@
+// Copyright 2021 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 page_test
+
+import (
+	"testing"
+
+	"github.com/gohugoio/hugo/hugolib"
+)
+
+func TestGroupByLocalizedDate(t *testing.T) {
+
+	files := `
+-- config.toml --
+defaultContentLanguage = 'en'
+defaultContentLanguageInSubdir = true
+[languages]
+[languages.en]
+title = 'My blog'
+weight = 1
+[languages.fr]
+title = 'Mon blogue'
+weight = 2
+[languages.nn]
+title = 'Bloggen min'
+weight = 3
+-- content/p1.md --
+---
+title: "Post 1"
+date: "2020-01-01"
+---
+-- content/p2.md --
+---
+title: "Post 2"
+date: "2020-02-01"
+---
+-- content/p1.fr.md --
+---
+title: "Post 1"
+date: "2020-01-01"
+---
+-- content/p2.fr.md --
+---
+title: "Post 2"
+date: "2020-02-01"
+---
+-- layouts/index.html --
+{{ range $k, $v := site.RegularPages.GroupByDate "January, 2006" }}{{ $k }}|{{ $v.Key }}|{{ $v.Pages }}{{ end }}
+
+	`
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+			NeedsOsFS:   true,
+		}).Build()
+
+	b.AssertFileContent("public/en/index.html", "0|February, 2020|Pages(1)1|January, 2020|Pages(1)")
+	b.AssertFileContent("public/fr/index.html", "0|février, 2020|Pages(1)1|janvier, 2020|Pages(1)")
+}
diff --git a/resources/page/page_matcher_test.go b/resources/page/page_matcher_test.go
index 846ab2c03..4a59dc502 100644
--- a/resources/page/page_matcher_test.go
+++ b/resources/page/page_matcher_test.go
@@ -14,10 +14,11 @@
 package page
 
 import (
-	"github.com/gohugoio/hugo/common/hugo"
 	"path/filepath"
 	"testing"
 
+	"github.com/gohugoio/hugo/common/hugo"
+
 	qt "github.com/frankban/quicktest"
 )
 
diff --git a/resources/page/pagegroup.go b/resources/page/pagegroup.go
index 18c98e70e..601af606a 100644
--- a/resources/page/pagegroup.go
+++ b/resources/page/pagegroup.go
@@ -26,6 +26,7 @@ import (
 	"github.com/gohugoio/hugo/common/collections"
 	"github.com/gohugoio/hugo/common/hreflect"
 	"github.com/gohugoio/hugo/compare"
+	"github.com/gohugoio/hugo/langs"
 
 	"github.com/gohugoio/hugo/resources/resource"
 )
@@ -219,7 +220,7 @@ func (p Pages) GroupByParam(key string, order ...string) (PagesGroup, error) {
 	return r, nil
 }
 
-func (p Pages) groupByDateField(sorter func(p Pages) Pages, formatter func(p Page) string, order ...string) (PagesGroup, error) {
+func (p Pages) groupByDateField(format string, sorter func(p Pages) Pages, getDate func(p Page) time.Time, order ...string) (PagesGroup, error) {
 	if len(p) < 1 {
 		return nil, nil
 	}
@@ -234,16 +235,24 @@ func (p Pages) groupByDateField(sorter func(p Pages) Pages, formatter func(p Pag
 		return nil, nil
 	}
 
-	date := formatter(sp[0].(Page))
+	firstPage := sp[0].(Page)
+	date := getDate(firstPage)
+
+	// Pages may be a mix of multiple languages, so we need to use the language
+	// for the currently rendered Site.
+	currentSite := firstPage.Site().Current()
+	formatter := langs.GetTimeFormatter(currentSite.Language())
+	formatted := formatter.Format(date, format)
 	var r []PageGroup
-	r = append(r, PageGroup{Key: date, Pages: make(Pages, 0)})
+	r = append(r, PageGroup{Key: formatted, Pages: make(Pages, 0)})
 	r[0].Pages = append(r[0].Pages, sp[0])
 
 	i := 0
 	for _, e := range sp[1:] {
-		date = formatter(e.(Page))
-		if r[i].Key.(string) != date {
-			r = append(r, PageGroup{Key: date})
+		date = getDate(e.(Page))
+		formatted := formatter.Format(date, format)
+		if r[i].Key.(string) != formatted {
+			r = append(r, PageGroup{Key: formatted})
 			i++
 		}
 		r[i].Pages = append(r[i].Pages, e)
@@ -259,10 +268,10 @@ func (p Pages) GroupByDate(format string, order ...string) (PagesGroup, error) {
 	sorter := func(p Pages) Pages {
 		return p.ByDate()
 	}
-	formatter := func(p Page) string {
-		return p.Date().Format(format)
+	getDate := func(p Page) time.Time {
+		return p.Date()
 	}
-	return p.groupByDateField(sorter, formatter, order...)
+	return p.groupByDateField(format, sorter, getDate, order...)
 }
 
 // GroupByPublishDate groups by the given page's PublishDate value in
@@ -273,10 +282,10 @@ func (p Pages) GroupByPublishDate(format string, order ...string) (PagesGroup, e
 	sorter := func(p Pages) Pages {
 		return p.ByPublishDate()
 	}
-	formatter := func(p Page) string {
-		return p.PublishDate().Format(format)
+	getDate := func(p Page) time.Time {
+		return p.PublishDate()
 	}
-	return p.groupByDateField(sorter, formatter, order...)
+	return p.groupByDateField(format, sorter, getDate, order...)
 }
 
 // GroupByExpiryDate groups by the given page's ExpireDate value in
@@ -287,10 +296,10 @@ func (p Pages) GroupByExpiryDate(format string, order ...string) (PagesGroup, er
 	sorter := func(p Pages) Pages {
 		return p.ByExpiryDate()
 	}
-	formatter := func(p Page) string {
-		return p.ExpiryDate().Format(format)
+	getDate := func(p Page) time.Time {
+		return p.ExpiryDate()
 	}
-	return p.groupByDateField(sorter, formatter, order...)
+	return p.groupByDateField(format, sorter, getDate, order...)
 }
 
 // GroupByLastmod groups by the given page's Lastmod value in
@@ -301,10 +310,10 @@ func (p Pages) GroupByLastmod(format string, order ...string) (PagesGroup, error
 	sorter := func(p Pages) Pages {
 		return p.ByLastmod()
 	}
-	formatter := func(p Page) string {
-		return p.Lastmod().Format(format)
+	getDate := func(p Page) time.Time {
+		return p.Lastmod()
 	}
-	return p.groupByDateField(sorter, formatter, order...)
+	return p.groupByDateField(format, sorter, getDate, order...)
 }
 
 // GroupByParamDate groups by a date set as a param on the page in
@@ -340,10 +349,10 @@ func (p Pages) GroupByParamDate(key string, format string, order ...string) (Pag
 		pageBy(pdate).Sort(r)
 		return r
 	}
-	formatter := func(p Page) string {
-		return dates[p].Format(format)
+	getDate := func(p Page) time.Time {
+		return dates[p]
 	}
-	return p.groupByDateField(sorter, formatter, order...)
+	return p.groupByDateField(format, sorter, getDate, order...)
 }
 
 // ProbablyEq wraps compare.ProbablyEqer
diff --git a/resources/page/pages_sort_test.go b/resources/page/pages_sort_test.go
index 85a1cda15..cf4e339ee 100644
--- a/resources/page/pages_sort_test.go
+++ b/resources/page/pages_sort_test.go
@@ -18,18 +18,17 @@ import (
 	"testing"
 	"time"
 
-	"github.com/gohugoio/hugo/htesting/hqt"
-	"github.com/gohugoio/hugo/source"
-
 	"github.com/gohugoio/hugo/resources/resource"
+	"github.com/google/go-cmp/cmp"
 
 	qt "github.com/frankban/quicktest"
 )
 
-var eq = qt.CmpEquals(hqt.DeepAllowUnexported(
-	&testPage{},
-	&source.FileInfo{},
-))
+var eq = qt.CmpEquals(
+	cmp.Comparer(func(p1, p2 testPage) bool {
+		return p1.path == p2.path && p1.weight == p2.weight
+	}),
+)
 
 func TestDefaultSort(t *testing.T) {
 	t.Parallel()
diff --git a/resources/page/site.go b/resources/page/site.go
index 3cc9989ee..b84f17914 100644
--- a/resources/page/site.go
+++ b/resources/page/site.go
@@ -37,6 +37,7 @@ type Site interface {
 	ServerPort() int
 	Title() string
 	Sites() Sites
+	Current() Site
 	Hugo() hugo.Info
 	BaseURL() template.URL
 	Taxonomies() any
@@ -82,6 +83,10 @@ func (t testSite) Sites() Sites {
 	return nil
 }
 
+func (t testSite) Current() Site {
+	return t
+}
+
 func (t testSite) IsServer() bool {
 	return false
 }
diff --git a/resources/page/testhelpers_test.go b/resources/page/testhelpers_test.go
index cee1f99e5..30b8e4dff 100644
--- a/resources/page/testhelpers_test.go
+++ b/resources/page/testhelpers_test.go
@@ -64,6 +64,7 @@ func newTestPageWithFile(filename string) *testPage {
 		currentSection: &testPage{
 			sectionEntries: []string{"a", "b", "c"},
 		},
+		site: testSite{l: langs.NewDefaultLanguage(config.New())},
 	}
 }