Added random weight selector test

mod/dynamicproxy/loadbalance/originPicker_test.go

@@ -0,0 +1,100 @@
+package loadbalance
+
+import (
+	"fmt"
+	"math"
+	"math/rand"
+	"testing"
+	"time"
+)
+
+// func getRandomUpstreamByWeight(upstreams []*Upstream) (*Upstream, int, error) { ... }
+func TestRandomUpstreamSelection(t *testing.T) {
+	rand.Seed(time.Now().UnixNano()) // Seed for randomness
+
+	// Define some test upstreams
+	upstreams := []*Upstream{
+		{
+			OriginIpOrDomain:         "192.168.1.1:8080",
+			RequireTLS:               false,
+			SkipCertValidations:      false,
+			SkipWebSocketOriginCheck: false,
+			Weight:                   1,
+			MaxConn:                  0, // No connection limit for now
+		},
+		{
+			OriginIpOrDomain:         "192.168.1.2:8080",
+			RequireTLS:               false,
+			SkipCertValidations:      false,
+			SkipWebSocketOriginCheck: false,
+			Weight:                   1,
+			MaxConn:                  0,
+		},
+		{
+			OriginIpOrDomain:         "192.168.1.3:8080",
+			RequireTLS:               true,
+			SkipCertValidations:      true,
+			SkipWebSocketOriginCheck: true,
+			Weight:                   1,
+			MaxConn:                  0,
+		},
+		{
+			OriginIpOrDomain:         "192.168.1.4:8080",
+			RequireTLS:               true,
+			SkipCertValidations:      true,
+			SkipWebSocketOriginCheck: true,
+			Weight:                   1,
+			MaxConn:                  0,
+		},
+	}
+
+	// Track how many times each upstream is selected
+	selectionCount := make(map[string]int)
+	totalPicks := 10000 // Number of times to call getRandomUpstreamByWeight
+	//expectedPickCount := totalPicks / len(upstreams) // Ideal count for each upstream
+
+	// Pick upstreams and record their selection count
+	for i := 0; i < totalPicks; i++ {
+		upstream, _, err := getRandomUpstreamByWeight(upstreams)
+		if err != nil {
+			t.Fatalf("Error getting random upstream: %v", err)
+		}
+		selectionCount[upstream.OriginIpOrDomain]++
+	}
+
+	// Condition 1: Ensure every upstream has been picked at least once
+	for _, upstream := range upstreams {
+		if selectionCount[upstream.OriginIpOrDomain] == 0 {
+			t.Errorf("Upstream %s was never selected", upstream.OriginIpOrDomain)
+		}
+	}
+
+	// Condition 2: Check that the distribution is within 1-2 standard deviations
+	counts := make([]float64, len(upstreams))
+	for i, upstream := range upstreams {
+		counts[i] = float64(selectionCount[upstream.OriginIpOrDomain])
+	}
+
+	mean := float64(totalPicks) / float64(len(upstreams))
+	stddev := calculateStdDev(counts, mean)
+
+	tolerance := 2 * stddev // Allowing up to 2 standard deviations
+	for i, count := range counts {
+		if math.Abs(count-mean) > tolerance {
+			t.Errorf("Selection of upstream %s is outside acceptable range: %v picks (mean: %v, stddev: %v)", upstreams[i].OriginIpOrDomain, count, mean, stddev)
+		}
+	}
+
+	fmt.Println("Selection count:", selectionCount)
+	fmt.Printf("Mean: %.2f, StdDev: %.2f\n", mean, stddev)
+}
+
+// Helper function to calculate standard deviation
+func calculateStdDev(data []float64, mean float64) float64 {
+	var sumOfSquares float64
+	for _, value := range data {
+		sumOfSquares += (value - mean) * (value - mean)
+	}
+	variance := sumOfSquares / float64(len(data))
+	return math.Sqrt(variance)
+}