content: /*
   * Copyright (C) 2019-2025 Lightbend Inc. <https://www.lightbend.com>
   */
  
  package akka.stream.javadsl;
  
  import static akka.NotUsed.notUsed;
  import static org.junit.Assert.assertEquals;
  
  import akka.NotUsed;
  import akka.japi.Pair;
  import akka.stream.StreamTest;
  import akka.testkit.AkkaJUnitActorSystemResource;
  import akka.testkit.AkkaSpec;
  import java.util.List;
  import java.util.concurrent.CompletionStage;
  import java.util.concurrent.TimeUnit;
  import org.junit.ClassRule;
  import org.junit.Test;
  
  public class FlowWithContextTest extends StreamTest {
  
    public FlowWithContextTest() {
      super(actorSystemResource);
    }
  
    @ClassRule
    public static AkkaJUnitActorSystemResource actorSystemResource =
        new AkkaJUnitActorSystemResource("FlowWithContextTest", AkkaSpec.testConf());
  
    @Test
    public void simpleCaseHappyPath() throws Exception {
      final FlowWithContext<Integer, String, Integer, String, NotUsed> flow =
          FlowWithContext.create();
  
      final CompletionStage<List<Pair<Integer, String>>> result =
          Source.single(new Pair<>(1, "context"))
              .via(flow.map(n -> n + 1).mapContext(ctx -> ctx + "-mapped"))
              .runWith(Sink.seq(), system);
      final List<Pair<Integer, String>> pairs = result.toCompletableFuture().get(3, TimeUnit.SECONDS);
      assertEquals(1, pairs.size());
      assertEquals(Integer.valueOf(2), pairs.get(0).first());
      assertEquals("context-mapped", pairs.get(0).second());
    }
  
    @Test
    public void mustAllowComposingFlows() throws Exception {
      final FlowWithContext<Integer, NotUsed, Integer, NotUsed, NotUsed> flow1 =
          FlowWithContext.create();
      final FlowWithContext<Integer, NotUsed, String, NotUsed, NotUsed> flow2 =
          FlowWithContext.<Integer, NotUsed>create().map(Object::toString);
  
      final FlowWithContext<Integer, NotUsed, String, NotUsed, NotUsed> flow3 = flow1.via(flow2);
  
      final CompletionStage<List<Pair<String, NotUsed>>> result =
          Source.single(new Pair<>(1, notUsed())).via(flow3.asFlow()).runWith(Sink.seq(), system);
  
      List<Pair<String, NotUsed>> pairs = result.toCompletableFuture().get(3, TimeUnit.SECONDS);
  
      assertEquals(1, pairs.size());
      assertEquals("1", pairs.get(0).first());
      assertEquals(notUsed(), pairs.get(0).second());
    }
  }
  