diff --git a/akka-cluster-sharding/src/test/scala/akka/cluster/sharding/ClusterShardingInternalsSpec.scala b/akka-cluster-sharding/src/test/scala/akka/cluster/sharding/ClusterShardingInternalsSpec.scala
index 232aa80585..39bc19c097 100644
--- a/akka-cluster-sharding/src/test/scala/akka/cluster/sharding/ClusterShardingInternalsSpec.scala
+++ b/akka-cluster-sharding/src/test/scala/akka/cluster/sharding/ClusterShardingInternalsSpec.scala
@@ -4,14 +4,12 @@
 
 package akka.cluster.sharding
 
-import akka.actor.{ Actor, ExtendedActorSystem, NoSerializationVerificationNeeded, PoisonPill, Props }
+import akka.actor.{ Actor, ActorRef, ExtendedActorSystem, NoSerializationVerificationNeeded, PoisonPill, Props }
+import akka.cluster.ClusterSettings.DataCenter
 import akka.cluster.sharding.ShardCoordinator.Internal.ShardStopped
-import akka.cluster.sharding.ShardCoordinator.ShardAllocationStrategy
-import akka.cluster.sharding.ShardRegion.HandOffStopper
+import akka.cluster.sharding.ShardCoordinator.LeastShardAllocationStrategy
+import akka.cluster.sharding.ShardRegion.{ ExtractEntityId, ExtractShardId, HandOffStopper, Msg }
 import akka.testkit.{ AkkaSpec, TestProbe }
-import org.mockito.ArgumentMatchers
-import org.mockito.Mockito._
-import org.scalatestplus.mockito.MockitoSugar
 
 import scala.concurrent.duration._
 
@@ -32,10 +30,29 @@ class ClusterShardingInternalsSpec extends AkkaSpec("""
     |akka.actor.provider = cluster
     |akka.remote.classic.netty.tcp.port = 0
     |akka.remote.artery.canonical.port = 0
-    |""".stripMargin) with MockitoSugar {
+    |""".stripMargin) {
   import ClusterShardingInternalsSpec._
 
-  val clusterSharding = spy(new ClusterSharding(system.asInstanceOf[ExtendedActorSystem]))
+  case class StartingProxy(
+      typeName: String,
+      role: Option[String],
+      dataCenter: Option[DataCenter],
+      extractEntityId: ExtractEntityId,
+      extractShardId: ExtractShardId)
+
+  val probe = TestProbe()
+
+  val clusterSharding = new ClusterSharding(system.asInstanceOf[ExtendedActorSystem]) {
+    override def startProxy(
+        typeName: String,
+        role: Option[String],
+        dataCenter: Option[DataCenter],
+        extractEntityId: ExtractEntityId,
+        extractShardId: ExtractShardId): ActorRef = {
+      probe.ref ! StartingProxy(typeName, role, dataCenter, extractEntityId, extractShardId)
+      ActorRef.noSender
+    }
+  }
 
   "ClusterSharding" must {
 
@@ -43,8 +60,8 @@ class ClusterShardingInternalsSpec extends AkkaSpec("""
 
       val settingsWithRole = ClusterShardingSettings(system).withRole("nonExistingRole")
       val typeName = "typeName"
-      val extractEntityId = mock[ShardRegion.ExtractEntityId]
-      val extractShardId = mock[ShardRegion.ExtractShardId]
+      val extractEntityId: ExtractEntityId = { case msg: Msg => ("42", msg) }
+      val extractShardId: ExtractShardId = _ => "37"
 
       clusterSharding.start(
         typeName = typeName,
@@ -52,15 +69,10 @@ class ClusterShardingInternalsSpec extends AkkaSpec("""
         settings = settingsWithRole,
         extractEntityId = extractEntityId,
         extractShardId = extractShardId,
-        allocationStrategy = mock[ShardAllocationStrategy],
+        allocationStrategy = new LeastShardAllocationStrategy(3, 4),
         handOffStopMessage = PoisonPill)
 
-      verify(clusterSharding).startProxy(
-        ArgumentMatchers.eq(typeName),
-        ArgumentMatchers.eq(settingsWithRole.role),
-        ArgumentMatchers.eq(None),
-        ArgumentMatchers.eq(extractEntityId),
-        ArgumentMatchers.eq(extractShardId))
+      probe.expectMsg(StartingProxy(typeName, settingsWithRole.role, None, extractEntityId, extractShardId))
     }
 
     "stop entities from HandOffStopper even if the entity doesn't handle handOffStopMessage" in {
diff --git a/akka-docs/src/main/paradox/stream/operators/Source-or-Flow/fold.md b/akka-docs/src/main/paradox/stream/operators/Source-or-Flow/fold.md
index ff38d53cfa..a12b4ecf4b 100644
--- a/akka-docs/src/main/paradox/stream/operators/Source-or-Flow/fold.md
+++ b/akka-docs/src/main/paradox/stream/operators/Source-or-Flow/fold.md
@@ -19,6 +19,7 @@ completes, the current value is emitted downstream.
 
 Note that the `zero` value must be immutable.
 
+## Reactive Streams semantics
 
 @@@div { .callout }
 
diff --git a/project/Dependencies.scala b/project/Dependencies.scala
index 1bd1987062..ae6ae9f0e5 100644
--- a/project/Dependencies.scala
+++ b/project/Dependencies.scala
@@ -208,8 +208,7 @@ object Dependencies {
         Provided.levelDBNative,
         Test.junit,
         Test.scalatest.value,
-        Test.commonsIo,
-        Test.mockito)
+        Test.commonsIo)
 
   val clusterMetrics = l ++= Seq(Provided.sigarLoader, Test.slf4jJul, Test.slf4jLog4j, Test.logback, Test.mockito)