Add receiveN to JavaTestKit. Fixes #3029

akka-docs/rst/java/code/docs/testkit/TestKitDocTest.java

@@ -206,6 +206,11 @@ public class TestKitDocTest {
       final Number j     = expectMsgAnyClassOf(Integer.class, Long.class);
       expectNoMsg();
       //#test-expect
+      getRef().tell("receveN-1", null);
+      getRef().tell("receveN-2", null);
+      //#test-expect
+      final Object[] two = receiveN(2);
+      //#test-expect
       assertEquals("hello", hello);
       assertEquals("hello", any);
       assertEquals(42, i);

akka-docs/rst/java/testing.rst

@@ -235,6 +235,11 @@ obey the innermost enclosing :class:`Within` as detailed :ref:`below
     message has been received before calling this method which has not been
     removed from the queue using one of the other methods.
 
+  * :meth:`Object[] receiveN(int n, Duration max)`
+
+    ``n`` messages must be received within the given time; the received
+    messages are returned.
+
 For cases which require more refined conditions there are constructs which take
 code blocks: