fix quickselect.

eventstore/lmdb/utils_test.go

@@ -7,21 +7,61 @@ import (
 )
 
 func TestQuickselect(t *testing.T) {
-	its := iterators{
-		{last: 781},
-		{last: 900},
-		{last: 1},
-		{last: 81},
-		{last: 325},
-		{last: 781},
-		{last: 562},
-		{last: 81},
-		{last: 444},
+	{
+		its := iterators{
+			{last: 781},
+			{last: 900},
+			{last: 1},
+			{last: 81},
+			{last: 325},
+			{last: 781},
+			{last: 562},
+			{last: 81},
+			{last: 444},
+		}
+
+		its.quickselect(3)
+		require.ElementsMatch(t,
+			[]uint32{its[0].last, its[1].last, its[2].last},
+			[]uint32{900, 781, 781},
+		)
 	}
 
-	its.quickselect(3, 0, len(its))
-	require.ElementsMatch(t, its[len(its)-3:], iterators{{last: 900}, {last: 781}, {last: 781}})
+	{
+		its := iterators{
+			{last: 781},
+			{last: 781},
+			{last: 900},
+			{last: 1},
+			{last: 87},
+			{last: 315},
+			{last: 789},
+			{last: 500},
+			{last: 812},
+			{last: 306},
+			{last: 612},
+			{last: 444},
+			{last: 59},
+			{last: 441},
+			{last: 901},
+			{last: 901},
+			{last: 2},
+			{last: 81},
+			{last: 325},
+			{last: 781},
+			{last: 562},
+			{last: 81},
+			{last: 326},
+			{last: 662},
+			{last: 444},
+			{last: 81},
+			{last: 444},
+		}
 
-	its.quickselect(4, 0, len(its))
-	require.ElementsMatch(t, its[len(its)-4:], iterators{{last: 562}, {last: 900}, {last: 781}, {last: 781}})
+		its.quickselect(6)
+		require.ElementsMatch(t,
+			[]uint32{its[0].last, its[1].last, its[2].last, its[3].last, its[4].last, its[5].last},
+			[]uint32{901, 900, 901, 781, 812, 789},
+		)
+	}
 }