runtime/jitter: allow overwrite of defaults

Signed-off-by: Hidde Beydals <hidde@hhh.computer>

runtime/jitter/interval.go

@@ -27,7 +27,8 @@ import (
 )
 
 const (
-	flagIntervalJitter = "interval-jitter-percent"
+	flagIntervalJitter              = "interval-jitter-percentage"
+	defaultIntervalJitterPercentage = 10
 )
 
 var (
@@ -101,9 +102,21 @@ type Interval struct {
 	Percentage uint8
 }
 
-// BindFlags will parse the given pflag.FlagSet and load the interval jitter.
+// BindFlags will parse the given pflag.FlagSet and load the interval jitter
+// with the default value of 10%.
 func (o *Interval) BindFlags(fs *pflag.FlagSet) {
-	fs.Uint8Var(&o.Percentage, flagIntervalJitter, 0,
+	o.BindFlagsWithDefault(fs, -1)
+}
+
+// BindFlagsWithDefault will parse the given pflag.FlagSet and load the interval
+// jitter. The defaultPercentage is used to set the default value for the
+// interval jitter percentage. If the defaultPercentage is negative, then the
+// default value (of 10%) will be used.
+func (o *Interval) BindFlagsWithDefault(fs *pflag.FlagSet, defaultPercentage int) {
+	if defaultPercentage < 0 {
+		defaultPercentage = defaultIntervalJitterPercentage
+	}
+	fs.Uint8Var(&o.Percentage, flagIntervalJitter, uint8(defaultPercentage),
 		"Percentage of jitter to apply to interval durations. A value of 10 "+
 			"will apply a jitter of +/-10% to the interval duration. It cannot be "+
 			"negative, and must be less than 100.")

runtime/jitter/interval_test.go

@@ -92,9 +92,40 @@ func TestInterval_BindFlags(t *testing.T) {
 	fs := pflag.NewFlagSet("test", pflag.ContinueOnError)
 	interval.BindFlags(fs)
 
-	err := fs.Set(flagIntervalJitter, "20")
-	g.Expect(err).ToNot(HaveOccurred())
-	g.Expect(interval.Percentage).To(Equal(uint8(20)))
+	g.Expect(interval.Percentage).To(Equal(uint8(defaultIntervalJitterPercentage)))
+}
+
+func TestInterval_BindFlagsWithDefault(t *testing.T) {
+	g := NewWithT(t)
+
+	t.Run("with default fallback", func(t *testing.T) {
+		interval := &Interval{}
+
+		fs := pflag.NewFlagSet("test", pflag.ContinueOnError)
+		interval.BindFlagsWithDefault(fs, -1)
+
+		g.Expect(interval.Percentage).To(Equal(uint8(defaultIntervalJitterPercentage)))
+	})
+
+	t.Run("with custom default", func(t *testing.T) {
+		interval := &Interval{}
+
+		fs := pflag.NewFlagSet("test", pflag.ContinueOnError)
+		interval.BindFlagsWithDefault(fs, 50)
+
+		g.Expect(interval.Percentage).To(Equal(uint8(50)))
+	})
+
+	t.Run("with flag override", func(t *testing.T) {
+		interval := &Interval{}
+
+		fs := pflag.NewFlagSet("test", pflag.ContinueOnError)
+		interval.BindFlagsWithDefault(fs, 0)
+
+		err := fs.Set("interval-jitter-percentage", "25")
+		g.Expect(err).ToNot(HaveOccurred())
+		g.Expect(interval.Percentage).To(Equal(uint8(25)))
+	})
 }
 
 func TestInterval_SetGlobalJitter(t *testing.T) {