Add clock cli flag

Close #8787

common/htime/time.go

@@ -17,6 +17,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/bep/clock"
 	"github.com/spf13/cast"
 
 	toml "github.com/pelletier/go-toml/v2"
@@ -74,6 +75,7 @@ var (
 		"November",
 		"December",
 	}
+	Clock = clock.Start(time.Now())
 )
 
 func NewTimeFormatter(ltr locales.Translator) TimeFormatter {
@@ -148,3 +150,13 @@ func ToTimeInDefaultLocationE(i any, location *time.Location) (tim time.Time, er
 	}
 	return cast.ToTimeInDefaultLocationE(i, location)
 }
+
+// Now returns time.Now() or time value based on`clock` flag.
+// Use this function to fake time inside hugo.
+func Now() time.Time {
+	return Clock.Now()
+}
+
+func Since(t time.Time) time.Duration {
+	return Clock.Now().Sub(t)
+}

common/loggers/loggers.go

@@ -24,6 +24,7 @@ import (
 	"runtime"
 	"time"
 
+	"github.com/gohugoio/hugo/common/htime"
 	"github.com/gohugoio/hugo/common/terminal"
 
 	jww "github.com/spf13/jwalterweatherman"
@@ -176,7 +177,7 @@ func (l *logger) Out() io.Writer {
 // PrintTimerIfDelayed prints a time statement to the FEEDBACK logger
 // if considerable time is spent.
 func (l *logger) PrintTimerIfDelayed(start time.Time, name string) {
-	elapsed := time.Since(start)
+	elapsed := htime.Since(start)
 	milli := int(1000 * elapsed.Seconds())
 	if milli < 500 {
 		return
@@ -185,7 +186,7 @@ func (l *logger) PrintTimerIfDelayed(start time.Time, name string) {
 }
 
 func (l *logger) PrintTimer(start time.Time, name string) {
-	elapsed := time.Since(start)
+	elapsed := htime.Since(start)
 	milli := int(1000 * elapsed.Seconds())
 	l.Printf("%s in %v ms", name, milli)
 }