feat: public API, SEO and existing surfaces

test/site_languages_http_test.go

@@ -106,15 +106,15 @@ func TestSiteLanguagesReading(t *testing.T) {
 						t.Errorf("entry = %+v", entry)
 					}
 					row := localization.Row{Tag: entry.Lang, SocialLocale: entry.SocialLocale}
-					if !sameText(localization.EffectiveSocialLocale(row), c.effective) {
-						t.Errorf("effective = %v", localization.EffectiveSocialLocale(row))
+					if !sameText(localization.EffectiveSocialLocale(row, nil), c.effective) {
+						t.Errorf("effective = %v", localization.EffectiveSocialLocale(row, nil))
 					}
 				}
 			})
 		}
 	})
 
-	t.Run("Only the explicit value and the tag's own region resolve the social locale", func(t *testing.T) {
+	t.Run("A bare tag borrows the region of Site.Locale", func(t *testing.T) {
 		e := newLocalizationEnv(t)
 		e.sites.seed(5, "Atelier", "atelier", false)
 		gb := "en-GB"
@@ -125,7 +125,27 @@ func TestSiteLanguagesReading(t *testing.T) {
 
 		view := decodeLanguagesView(t, e.owner(t, http.MethodGet, "/v1/site/atelier/languages", ""))
 
-		if view.Languages[0].State != "not_set" {
+		if view.Languages[0].State != "derived" {
+			t.Errorf("state = %q", view.Languages[0].State)
+		}
+		row := localization.Row{Tag: "en"}
+		if !sameText(localization.EffectiveSocialLocale(row, &gb), localeOf("en_GB")) {
+			t.Errorf("effective = %v", localization.EffectiveSocialLocale(row, &gb))
+		}
+	})
+
+	t.Run("No region anywhere stays not set", func(t *testing.T) {
+		e := newLocalizationEnv(t)
+		e.sites.seed(5, "Atelier", "atelier", false)
+		bare := "en"
+		stored := e.sites.sites[5]
+		stored.Locale = &bare
+		e.sites.sites[5] = stored
+		e.seedRows(5, localization.Row{Tag: "en", IsDefault: true, Enabled: true, Confirmed: true})
+
+		view := decodeLanguagesView(t, e.owner(t, http.MethodGet, "/v1/site/atelier/languages", ""))
+
+		if view.Languages[0].State != "not_set" || localization.EffectiveSocialLocale(localization.Row{Tag: "en"}, &bare) != nil {
 			t.Errorf("state = %q", view.Languages[0].State)
 		}
 	})