Remove usage of Java assert in tests (#30220) (#30227)

akka-docs/src/test/java/jdocs/stream/StreamTestKitDocTest.java

@@ -20,6 +20,7 @@ import jdocs.AbstractJavaTest;
 import akka.testkit.javadsl.TestKit;
 import org.junit.*;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
 
 import akka.actor.*;
 import akka.japi.Pair;
@@ -54,7 +55,7 @@ public class StreamTestKitDocTest extends AbstractJavaTest {
     final CompletionStage<Integer> future =
         Source.from(Arrays.asList(1, 2, 3, 4)).runWith(sinkUnderTest, system);
     final Integer result = future.toCompletableFuture().get(3, TimeUnit.SECONDS);
-    assert (result == 20);
+    assertEquals(20, result.intValue());
     // #strict-collection
   }
 
@@ -66,7 +67,7 @@ public class StreamTestKitDocTest extends AbstractJavaTest {
     final CompletionStage<List<Integer>> future =
         sourceUnderTest.take(10).runWith(Sink.seq(), system);
     final List<Integer> result = future.toCompletableFuture().get(3, TimeUnit.SECONDS);
-    assertEquals(result, Collections.nCopies(10, 2));
+    assertEquals(Collections.nCopies(10, 2), result);
     // #grouped-infinite
   }
 
@@ -81,7 +82,7 @@ public class StreamTestKitDocTest extends AbstractJavaTest {
             .via(flowUnderTest)
             .runWith(Sink.fold(0, (agg, next) -> agg + next), system);
     final Integer result = future.toCompletableFuture().get(3, TimeUnit.SECONDS);
-    assert (result == 10);
+    assertEquals(10, result.intValue());
     // #folded-stream
   }
 
@@ -151,7 +152,7 @@ public class StreamTestKitDocTest extends AbstractJavaTest {
     ref.tell(Done.getInstance(), ActorRef.noSender());
 
     final String result = future.toCompletableFuture().get(1, TimeUnit.SECONDS);
-    assertEquals(result, "123");
+    assertEquals("123", result);
     // #source-actorref
   }
 
@@ -192,13 +193,10 @@ public class StreamTestKitDocTest extends AbstractJavaTest {
     final CompletionStage<Integer> future = probeAndCompletionStage.second();
     probe.sendError(new Exception("boom"));
 
-    try {
-      future.toCompletableFuture().get(3, TimeUnit.SECONDS);
-      assert false;
-    } catch (ExecutionException ee) {
-      final Throwable exception = ee.getCause();
-      assertEquals(exception.getMessage(), "boom");
-    }
+    ExecutionException exception =
+        Assert.assertThrows(
+            ExecutionException.class, () -> future.toCompletableFuture().get(3, TimeUnit.SECONDS));
+    assertEquals("boom", exception.getCause().getMessage());
     // #injecting-failure
   }
 
@@ -232,7 +230,7 @@ public class StreamTestKitDocTest extends AbstractJavaTest {
 
     pub.sendError(new Exception("Power surge in the linear subroutine C-47!"));
     final Throwable ex = sub.expectError();
-    assert (ex.getMessage().contains("C-47"));
+    assertTrue(ex.getMessage().contains("C-47"));
     // #test-source-and-sink
   }
 }