adapt testWaitForPendingSeqNo to stricter operation recovery range

Before we use to ship anything in the translog above a certain point. #27580 changed to have a strict upper bound.

core/src/test/java/org/elasticsearch/index/replication/RecoveryDuringReplicationTests.java

@@ -58,10 +58,12 @@
 import java.util.concurrent.atomic.AtomicReference;
 
 import static org.hamcrest.Matchers.anyOf;
+import static org.hamcrest.Matchers.both;
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThanOrEqualTo;
 import static org.hamcrest.Matchers.lessThan;
+import static org.hamcrest.Matchers.lessThanOrEqualTo;
 import static org.hamcrest.Matchers.not;
 
 public class RecoveryDuringReplicationTests extends ESIndexLevelReplicationTestCase {
@@ -390,7 +392,8 @@ public long indexTranslogOperations(List<Translog.Operation> operations, int tot
             recoveryStart.await();
 
             // index some more
-            docs += shards.indexDocs(randomInt(5));
+            final int indexedDuringRecovery = shards.indexDocs(randomInt(5));
+            docs += indexedDuringRecovery;
 
             assertFalse("recovery should wait on pending docs", opsSent.get());
 
@@ -401,7 +404,9 @@ public long indexTranslogOperations(List<Translog.Operation> operations, int tot
             recoveryFuture.get();
 
             assertThat(newReplica.recoveryState().getIndex().fileDetails(), empty());
-            assertThat(newReplica.recoveryState().getTranslog().recoveredOperations(), equalTo(docs));
+            assertThat(newReplica.recoveryState().getTranslog().recoveredOperations(),
+                // we don't know which of the inflight operations made it into the translog range we re-play
+                both(greaterThanOrEqualTo(docs-indexedDuringRecovery)).and(lessThanOrEqualTo(docs)));
 
             shards.assertAllEqual(docs);
         } finally {