Add test for winnerProba

Signed-off-by: Jakub Sztandera <kubuxu@protocol.ai>

chain/messagepool/block_proba_test.go

@@ -1,6 +1,11 @@
 package messagepool
 
-import "testing"
+import (
+	"math"
+	"math/rand"
+	"testing"
+	"time"
+)
 
 func TestBlockProbability(t *testing.T) {
 	mp := &MessagePool{}
@@ -13,3 +18,26 @@ func TestBlockProbability(t *testing.T) {
 		}
 	}
 }
+
+func TestWinnerProba(t *testing.T) {
+	rand.Seed(time.Now().UnixNano())
+	const N = 1000000
+	winnerProba := noWinnersProb()
+	sum := 0
+	for i := 0; i < N; i++ {
+		minersRand := rand.Float64()
+		j := 0
+		for ; j < MaxBlocks; j++ {
+			minersRand -= winnerProba[j]
+			if minersRand < 0 {
+				break
+			}
+		}
+		sum += j
+	}
+
+	if avg := float64(sum) / N; math.Abs(avg-5) > 0.01 {
+		t.Fatalf("avg too far off: %f", avg)
+	}
+
+}