Show whether the status on / and /status is fresh (closes #152)

Each page's script turns a one-character braille spinner next to the
status whenever a stats answer counts more messages than the one
before. Its colour cycles as rtnetmon's does. A separate check runs
every second. Once no such answer has come for three refresh periods,
15 seconds on / and 6 on /status, it shows "stale" and the seconds
since, in the page's disconnected colour. A failed or hung request
counts as no fresh answer. On / the card has no room beside
"Connected", so the indicator sits on the line under it. A test renders
both pages and checks the indicator follows the status element.

Model: opus-5-5

internal/templates/templates_test.go

@@ -9,6 +9,20 @@ import (
 	"git.eeqj.de/sneak/routewatch/internal/templates"
 )
 
+// renderPage renders a page with the data every page needs.
+func renderPage(t *testing.T, tmpl *template.Template) string {
+	t.Helper()
+
+	var page bytes.Buffer
+
+	err := tmpl.Execute(&page, struct{ CSPNonce string }{})
+	if err != nil {
+		t.Fatalf("rendering the page: %v", err)
+	}
+
+	return page.String()
+}
+
 // TestFooterLicense renders the home and status pages and expects each footer
 // to name the licence in LICENSE, MIT, and not WTFPL.
 func TestFooterLicense(t *testing.T) {
@@ -28,14 +42,7 @@ func TestFooterLicense(t *testing.T) {
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 
-			var page bytes.Buffer
-
-			err := tmpl.Execute(&page, struct{ CSPNonce string }{})
-			if err != nil {
-				t.Fatalf("rendering the page: %v", err)
-			}
-
-			_, footer, found := strings.Cut(page.String(), "<footer")
+			_, footer, found := strings.Cut(renderPage(t, tmpl), "<footer")
 			if !found {
 				t.Fatal("the page has no footer")
 			}
@@ -52,3 +59,42 @@ func TestFooterLicense(t *testing.T) {
 		})
 	}
 }
+
+// TestFreshnessIndicator renders the home and status pages and expects each to
+// have, right after the status element, the element where the page's script
+// shows its spinner or "stale".
+func TestFreshnessIndicator(t *testing.T) {
+	t.Parallel()
+
+	pages := map[string]struct {
+		tmpl      *template.Template
+		status    string
+		indicator string
+	}{
+		"index": {
+			tmpl:      templates.IndexTemplate(),
+			status:    `<span id="stat-status">-</span>`,
+			indicator: `<span id="freshness"></span>`,
+		},
+		"status": {
+			tmpl:      templates.StatusTemplate(),
+			status:    `<span class="metric-value" id="connected">-</span>`,
+			indicator: `<span class="metric-value" id="freshness"></span>`,
+		},
+	}
+
+	for name, page := range pages {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			_, afterStatus, found := strings.Cut(renderPage(t, page.tmpl), page.status)
+			if !found {
+				t.Fatalf("the page has no status element %s", page.status)
+			}
+
+			if !strings.HasPrefix(strings.TrimSpace(afterStatus), page.indicator) {
+				t.Errorf("the status element is not followed by %s", page.indicator)
+			}
+		})
+	}
+}