Fix test because of jitter

client/restarts.go

@@ -7,6 +7,9 @@ import (
 	"github.com/hashicorp/nomad/nomad/structs"
 )
 
+// jitter is the percent of jitter added to restart delays.
+const jitter = 0.25
+
 func newRestartTracker(policy *structs.RestartPolicy) *RestartTracker {
 	return &RestartTracker{
 		startTime: time.Now(),
@@ -57,8 +60,8 @@ func (r *RestartTracker) shouldRestart(exitCode int) bool {
 // jitter returns the delay time plus a jitter.
 func (r *RestartTracker) jitter() time.Duration {
 	d := r.policy.Delay.Nanoseconds()
-	j := r.rand.Int63n(d) / 4 // Up to 25% jitter
-	return time.Duration(d + j)
+	j := float64(r.rand.Int63n(d)) * jitter
+	return time.Duration(d + int64(j))
 }
 
 // Returns a tracker that never restarts.

client/restarts_test.go

@@ -17,6 +17,13 @@ func testPolicy(success bool, mode string) *structs.RestartPolicy {
 	}
 }
 
+// withinJitter is a helper that returns whether the returned delay is within
+// the jitter.
+func withinJitter(expected, actual time.Duration) bool {
+	return float64((actual.Nanoseconds()-expected.Nanoseconds())/
+		expected.Nanoseconds()) <= jitter
+}
+
 func TestClient_RestartTracker_ModeDelay(t *testing.T) {
 	t.Parallel()
 	p := testPolicy(true, structs.RestartPolicyModeDelay)
@@ -26,8 +33,8 @@ func TestClient_RestartTracker_ModeDelay(t *testing.T) {
 		if !actual {
 			t.Fatalf("NextRestart() returned %v, want %v", actual, true)
 		}
-		if when != p.Delay {
-			t.Fatalf("NextRestart() returned %v; want %v", when, p.Delay)
+		if !withinJitter(p.Delay, when) {
+			t.Fatalf("NextRestart() returned %v; want %v+jitter", when, p.Delay)
 		}
 	}
 
@@ -52,8 +59,8 @@ func TestClient_RestartTracker_ModeFail(t *testing.T) {
 		if !actual {
 			t.Fatalf("NextRestart() returned %v, want %v", actual, true)
 		}
-		if when != p.Delay {
-			t.Fatalf("NextRestart() returned %v; want %v", when, p.Delay)
+		if !withinJitter(p.Delay, when) {
+			t.Fatalf("NextRestart() returned %v; want %v+jitter", when, p.Delay)
 		}
 	}