metrics: Improve template metrics duration formatting

Fixes #15027

metrics/metrics.go

@@ -178,15 +178,29 @@ func (s *Store) WriteMetrics(w io.Writer) {
 	}
 
 	sort.Sort(bySum(results))
+
 	for _, v := range results {
 		if s.calculateHints {
-			fmt.Fprintf(w, "  %15s  %12s  %12s  %9d  %7.f  %6d  %5d  %s\n", v.sum, v.avg, v.max, v.cacheFactor, float64(v.cacheCount)/float64(v.count)*100, v.cacheCount, v.count, v.key)
+			fmt.Fprintf(w, "  %15s  %12s  %12s  %9d  %7.f  %6d  %5d  %s\n", formatDuration(v.sum), formatDuration(v.avg), formatDuration(v.max), v.cacheFactor, float64(v.cacheCount)/float64(v.count)*100, v.cacheCount, v.count, v.key)
 		} else {
-			fmt.Fprintf(w, "  %15s  %12s  %12s  %5d  %s\n", v.sum, v.avg, v.max, v.count, v.key)
+			fmt.Fprintf(w, "  %15s  %12s  %12s  %5d  %s\n", formatDuration(v.sum), formatDuration(v.avg), formatDuration(v.max), v.count, v.key)
 		}
 	}
 }
 
+func formatDuration(d time.Duration) string {
+	switch {
+	case d >= time.Second:
+		return fmt.Sprintf("%.2f  s", float64(d)/float64(time.Second)) // additional spacing between value and unit
+	case d >= time.Millisecond:
+		return fmt.Sprintf("%.2f ms", float64(d)/float64(time.Millisecond))
+	case d >= time.Microsecond:
+		return fmt.Sprintf("%.2f µs", float64(d)/float64(time.Microsecond))
+	default:
+		return fmt.Sprintf("%.2f ns", float64(d)/float64(time.Nanosecond))
+	}
+}
+
 // A result represents the calculated results for a given metric.
 type result struct {
 	key         string

metrics/metrics_test.go

@@ -17,6 +17,7 @@ import (
 	"html/template"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/gohugoio/hugo/resources/page"
 
@@ -66,3 +67,21 @@ func BenchmarkHowSimilar(b *testing.B) {
 		howSimilar(s1, s2)
 	}
 }
+
+func TestFormatDuration(t *testing.T) {
+	c := qt.New(t)
+	tests := []struct {
+		duration time.Duration
+		want     string
+	}{
+		{4*time.Second + 342*time.Millisecond, "4.34  s"}, // additional spacing between value and unit
+		{170*time.Millisecond + 289*time.Microsecond, "170.29 ms"},
+		{16*time.Microsecond + 90*time.Nanosecond, "16.09 µs"},
+		{147 * time.Nanosecond, "147.00 ns"},
+	}
+
+	for _, tt := range tests {
+		got := formatDuration(tt.duration)
+		c.Assert(got, qt.Equals, tt.want)
+	}
+}

tpl/partials/partials_integration_test.go

@@ -170,8 +170,8 @@ D1
 
 	got := buf.String()
 
-	// Get rid of all the durations, they are never the same.
-	durationRe := regexp.MustCompile(`\b[\.\d]*(ms|ns|µs|s)\b`)
+	// Get rid of all the durations, including the space and unit, they are never the same.
+	durationRe := regexp.MustCompile(`\b[\.\d]*\s*(ms|ns|µs|s)\b`)
 
 	normalize := func(s string) string {
 		s = durationRe.ReplaceAllString(s, "")