Remove warnings in akka stream testkit module (#26751)

akka-stream-testkit/src/main/scala/akka/stream/testkit/StreamTestKit.scala

@@ -83,6 +83,7 @@ object TestPublisher {
 
     type Self <: ManualProbe[I]
 
+    @ccompatUsedUntil213
     private val probe: TestProbe = TestProbe()
 
     //this is a way to pause receiving message from probe until subscription is done
@@ -419,7 +420,7 @@ object TestSubscriber {
       @annotation.tailrec
       def expectOneOf(all: immutable.Seq[I]): Unit = all match {
         case Nil =>
-        case list =>
+        case _ =>
           val next = expectNext()
           assert(all.contains(next), s"expected one of $all, but received $next")
           expectOneOf(all.diff(Seq(next)))
@@ -541,8 +542,8 @@ object TestSubscriber {
      */
     def expectNextOrError(): Either[Throwable, I] = {
       probe.fishForMessage(hint = s"OnNext(_) or error") {
-        case OnNext(element) => true
+        case OnNext(_)  => true
-        case OnError(cause)  => true
+        case OnError(_) => true
       } match {
         case OnNext(n: I @unchecked) => Right(n)
         case OnError(err)            => Left(err)
@@ -568,7 +569,7 @@ object TestSubscriber {
      */
     def expectNextOrComplete(): Either[OnComplete.type, I] = {
       probe.fishForMessage(hint = s"OnNext(_) or OnComplete") {
-        case OnNext(n)  => true
+        case OnNext(_)  => true
         case OnComplete => true
       } match {
         case OnComplete              => Left(OnComplete)

akka-stream-testkit/src/main/scala/akka/stream/testkit/scaladsl/StreamTestKit.scala

@@ -71,7 +71,7 @@ object StreamTestKit {
 
   /** INTERNAL API */
   @InternalApi private[testkit] def snapshotString(snapshot: StreamSnapshotImpl): String = {
-    val builder = StringBuilder.newBuilder
+    val builder = new StringBuilder()
     builder.append(s"activeShells (actor: ${snapshot.self}):\n")
     snapshot.activeInterpreters.foreach { shell =>
       builder.append("  ")

akka-stream-testkit/src/test/scala/akka/stream/testkit/TwoStreamsSetup.scala

@@ -10,7 +10,7 @@ import org.reactivestreams.Publisher
 
 abstract class TwoStreamsSetup extends BaseTwoStreamsSetup {
 
-  abstract class Fixture(b: GraphDSL.Builder[_]) {
+  abstract class Fixture {
     def left: Inlet[Int]
     def right: Inlet[Int]
     def out: Outlet[Outputs]

akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphConcatSpec.scala

@@ -14,7 +14,7 @@ class GraphConcatSpec extends TwoStreamsSetup {
 
   override type Outputs = Int
 
-  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture(b) {
+  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture {
     val concat = b.add(Concat[Outputs]())
 
     override def left: Inlet[Outputs] = concat.in(0)

akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphMergeLatestSpec.scala

@@ -17,7 +17,7 @@ class GraphMergeLatestSpec extends TwoStreamsSetup {
 
   override type Outputs = List[Int]
 
-  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture(b) {
+  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture {
     val merge = b.add(MergeLatest[Int](2))
 
     override def left: Inlet[Int] = merge.in(0)

akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphMergePreferredSpec.scala

@@ -15,7 +15,7 @@ class GraphMergePreferredSpec extends TwoStreamsSetup {
 
   override type Outputs = Int
 
-  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture(b) {
+  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture {
     val merge = b.add(MergePreferred[Outputs](1))
 
     override def left: Inlet[Outputs] = merge.preferred

akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphMergePrioritizedSpec.scala

@@ -15,7 +15,7 @@ class GraphMergePrioritizedSpec extends TwoStreamsSetup {
 
   override type Outputs = Int
 
-  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture(b) {
+  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture {
     val mergePrioritized = b.add(MergePrioritized[Outputs](Seq(2, 8)))
 
     override def left: Inlet[Outputs] = mergePrioritized.in(0)

akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphMergeSortedSpec.scala

@@ -14,7 +14,7 @@ class GraphMergeSortedSpec extends TwoStreamsSetup with GeneratorDrivenPropertyC
 
   override type Outputs = Int
 
-  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture(b) {
+  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture {
     val merge = b.add(new MergeSorted[Outputs])
 
     override def left: Inlet[Outputs] = merge.in0

akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphMergeSpec.scala

@@ -17,7 +17,7 @@ class GraphMergeSpec extends TwoStreamsSetup {
 
   override type Outputs = Int
 
-  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture(b) {
+  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture {
     val merge = b.add(Merge[Outputs](2))
 
     override def left: Inlet[Outputs] = merge.in(0)

akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphZipLatestWithSpec.scala

@@ -17,7 +17,7 @@ class GraphZipLatestWithSpec extends TwoStreamsSetup {
 
   override type Outputs = Int
 
-  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture(b) {
+  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture {
     val zip = b.add(ZipWith((_: Int) + (_: Int)))
     override def left: Inlet[Int] = zip.in0
     override def right: Inlet[Int] = zip.in1

akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphZipNSpec.scala

@@ -16,7 +16,7 @@ class GraphZipNSpec extends TwoStreamsSetup {
 
   override type Outputs = immutable.Seq[Int]
 
-  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture(b) {
+  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture {
     val zipN = b.add(ZipN[Int](2))
 
     override def left: Inlet[Int] = zipN.in(0)

akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphZipSpec.scala

@@ -16,7 +16,7 @@ class GraphZipSpec extends TwoStreamsSetup {
 
   override type Outputs = (Int, Int)
 
-  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture(b) {
+  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture {
     val zip = b.add(Zip[Int, Int]())
 
     override def left: Inlet[Int] = zip.in0

akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphZipWithNSpec.scala

@@ -15,7 +15,7 @@ class GraphZipWithNSpec extends TwoStreamsSetup {
 
   override type Outputs = Int
 
-  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture(b) {
+  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture {
     val zip = b.add(ZipWithN((_: immutable.Seq[Int]).sum)(2))
     override def left: Inlet[Int] = zip.in(0)
     override def right: Inlet[Int] = zip.in(1)

akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphZipWithSpec.scala

@@ -14,7 +14,7 @@ class GraphZipWithSpec extends TwoStreamsSetup {
 
   override type Outputs = Int
 
-  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture(b) {
+  override def fixture(b: GraphDSL.Builder[_]): Fixture = new Fixture {
     val zip = b.add(ZipWith((_: Int) + (_: Int)))
     override def left: Inlet[Int] = zip.in0
     override def right: Inlet[Int] = zip.in1

project/AkkaDisciplinePlugin.scala

@@ -35,7 +35,6 @@ object AkkaDisciplinePlugin extends AutoPlugin with ScalafixSupport {
     "akka-persistence-tck",
     "akka-persistence-typed",
     "akka-remote",
-    "akka-stream-testkit",
     "akka-stream-tests",
     "akka-stream-tests-tck",
     "akka-testkit")