Updated RandomFutureTime

loadtest/utils.go

@@ -91,11 +91,22 @@ func nextPowerOf2(val int) int {
 }
 
 // RandomFutureTime returns a random Unix timestamp, in milliseconds, in the interval
-// [now+deltaStart, now+maxUntil]
+// [now+deltaStart, now+deltaStart+maxUntil]
 func RandomFutureTime(deltaStart, maxUntil time.Duration) int64 {
 	now := time.Now()
-	diff := maxUntil - deltaStart
-	offset := deltaStart.Milliseconds() + rand.Int63n(diff.Milliseconds())
-	randomFutureTime := now.Add(time.Duration(offset) * time.Millisecond)
-	return randomFutureTime.UnixMilli()
+	start := now.Add(deltaStart)
+	start.Add(maxUntil)
+
+	// Generate a random duration between 0 and maxUntil
+	var randomDuration time.Duration
+	if maxUntil > 0 {
+		randomDuration = time.Duration(rand.Int63n(int64(maxUntil)))
+	} else {
+		randomDuration = time.Duration(0)
+	}
+
+	// Add the random duration to the start time
+	randomTime := start.Add(randomDuration)
+
+	return randomTime.Unix()
 }

loadtest/utils_test.go

@@ -0,0 +1,97 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package loadtest
+
+import (
+	"testing"
+	"time"
+)
+
+func TestRandomFutureTime(t *testing.T) {
+	deltaStart := 10 * time.Second
+	maxUntil := 5 * time.Minute
+
+	now := time.Now()
+	start := now.Add(deltaStart)
+	end := start.Add(maxUntil)
+
+	randomTime := RandomFutureTime(deltaStart, maxUntil)
+
+	if randomTime < start.Unix() || randomTime > end.Unix() {
+		t.Errorf("RandomFutureTime() = %v, want between %v and %v", randomTime, start.Unix(), end.Unix())
+	}
+}
+
+func TestRandomFutureTimeZeroDuration(t *testing.T) {
+	deltaStart := 0 * time.Second
+	maxUntil := 0 * time.Second
+
+	now := time.Now()
+	expectedTime := now.Unix()
+
+	randomTime := RandomFutureTime(deltaStart, maxUntil)
+
+	if randomTime != expectedTime {
+		t.Errorf("RandomFutureTime() = %v, want %v", randomTime, expectedTime)
+	}
+}
+
+func TestRandomFutureTimeNegativeDuration(t *testing.T) {
+	deltaStart := -10 * time.Second
+	maxUntil := -5 * time.Minute
+
+	now := time.Now()
+	start := now.Add(deltaStart)
+	end := start.Add(maxUntil)
+
+	randomTime := RandomFutureTime(deltaStart, maxUntil)
+
+	if randomTime < end.Unix() || randomTime > start.Unix() {
+		t.Errorf("RandomFutureTime() = %v, want between %v and %v", randomTime, end.Unix(), start.Unix())
+	}
+}
+
+func TestRandomFutureTimeMaxUntilZero(t *testing.T) {
+	deltaStart := 10 * time.Second
+	maxUntil := 0 * time.Second
+
+	now := time.Now()
+	expectedTime := now.Add(deltaStart).Unix()
+
+	randomTime := RandomFutureTime(deltaStart, maxUntil)
+
+	if randomTime != expectedTime {
+		t.Errorf("RandomFutureTime() = %v, want %v", randomTime, expectedTime)
+	}
+}
+
+func TestRandomFutureTimeDeltaStartZero(t *testing.T) {
+	deltaStart := 0 * time.Second
+	maxUntil := 5 * time.Minute
+
+	now := time.Now()
+	start := now
+	end := start.Add(maxUntil)
+
+	randomTime := RandomFutureTime(deltaStart, maxUntil)
+
+	if randomTime < start.Unix() || randomTime > end.Unix() {
+		t.Errorf("RandomFutureTime() = %v, want between %v and %v", randomTime, start.Unix(), end.Unix())
+	}
+}
+
+func TestRandomFutureTimeLargeDurations(t *testing.T) {
+	deltaStart := 100 * time.Hour
+	maxUntil := 1000 * time.Hour
+
+	now := time.Now()
+	start := now.Add(deltaStart)
+	end := start.Add(maxUntil)
+
+	randomTime := RandomFutureTime(deltaStart, maxUntil)
+
+	if randomTime < start.Unix() || randomTime > end.Unix() {
+		t.Errorf("RandomFutureTime() = %v, want between %v and %v", randomTime, start.Unix(), end.Unix())
+	}
+}