create EphemerySlotValidationService and test

services/beaconchain/src/main/java/tech/pegasys/teku/services/beaconchain/BeaconChainController.java

@@ -114,6 +114,7 @@
 import tech.pegasys.teku.spec.logic.common.statetransition.results.BlockImportResult;
 import tech.pegasys.teku.spec.logic.common.util.BlockRewardCalculatorUtil;
 import tech.pegasys.teku.spec.logic.versions.deneb.helpers.MiscHelpersDeneb;
+import tech.pegasys.teku.spec.networks.Eth2Network;
 import tech.pegasys.teku.statetransition.EpochCachePrimer;
 import tech.pegasys.teku.statetransition.LocalOperationAcceptedFilter;
 import tech.pegasys.teku.statetransition.MappedOperationPool;
@@ -532,6 +533,7 @@ public void initAll() {
     initRestAPI();
     initOperationsReOrgManager();
     initValidatorIndexCacheTracker();
+    initEphemeryValidationService();
   }
 
   private void initKeyValueStore() {
@@ -1148,6 +1150,15 @@ protected void initP2PNetwork() {
         new LocalOperationAcceptedFilter<>(p2pNetwork::publishSignedBlsToExecutionChange));
   }
 
+  protected void initEphemeryValidationService() {
+    Optional<Eth2Network> network = beaconConfig.eth2NetworkConfig().getEth2Network();
+    if (network.isPresent() && network.equals(Optional.of(Eth2Network.EPHEMERY))) {
+      final EphemerySlotValidationService slotValidationService =
+          new EphemerySlotValidationService();
+      eventChannels.subscribe(SlotEventsChannel.class, slotValidationService);
+    }
+  }
+
   protected Eth2P2PNetworkBuilder createEth2P2PNetworkBuilder() {
     return Eth2P2PNetworkBuilder.create();
   }

services/beaconchain/src/main/java/tech/pegasys/teku/services/beaconchain/EphemerySlotValidationService.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright Consensys Software Inc., 2024
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+
+package tech.pegasys.teku.services.beaconchain;
+
+import static tech.pegasys.teku.networks.EphemeryNetwork.MAX_EPHEMERY_SLOT;
+
+import tech.pegasys.teku.ethereum.events.SlotEventsChannel;
+import tech.pegasys.teku.infrastructure.async.SafeFuture;
+import tech.pegasys.teku.infrastructure.unsigned.UInt64;
+import tech.pegasys.teku.service.serviceutils.Service;
+
+public class EphemerySlotValidationService extends Service implements SlotEventsChannel {
+
+  public EphemerySlotValidationService() {}
+
+  @Override
+  public void onSlot(final UInt64 slot) {
+    if (slot.compareTo(MAX_EPHEMERY_SLOT) > 0) {
+      throw new IllegalStateException(
+          String.format(
+              "Slot %s exceeds maximum allowed slot %s for ephemery network",
+              slot, MAX_EPHEMERY_SLOT));
+    }
+  }
+
+  @Override
+  protected SafeFuture<?> doStart() {
+    return SafeFuture.COMPLETE;
+  }
+
+  @Override
+  protected SafeFuture<?> doStop() {
+    return SafeFuture.COMPLETE;
+  }
+}

services/beaconchain/src/test/java/tech/pegasys/teku/services/beaconchain/EphemerySlotValidationServiceTest.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright Consensys Software Inc., 2024
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+
+package tech.pegasys.teku.services.beaconchain;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.AssertionsForClassTypes.assertThatCode;
+import static org.assertj.core.api.AssertionsForClassTypes.assertThatThrownBy;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static tech.pegasys.teku.networks.EphemeryNetwork.MAX_EPHEMERY_SLOT;
+
+import java.util.Optional;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import tech.pegasys.teku.infrastructure.async.SafeFuture;
+import tech.pegasys.teku.infrastructure.unsigned.UInt64;
+import tech.pegasys.teku.spec.networks.Eth2Network;
+
+class EphemerySlotValidationServiceTest {
+  private EphemerySlotValidationService ephemerySlotValidationService;
+
+  @BeforeEach
+  void setUp() {
+    ephemerySlotValidationService = new EphemerySlotValidationService();
+  }
+
+  @Test
+  public void onSlot_shouldNotThrow_whenSlotIsValid() {
+    ephemerySlotValidationService.onSlot(UInt64.valueOf(MAX_EPHEMERY_SLOT));
+  }
+
+  @Test
+  public void onSlot_shouldThrowException_whenSlotExceedsMaxEphemerySlot_forEphemeryNetwork() {
+    final Eth2Network network = Eth2Network.EPHEMERY;
+    final Optional<Eth2Network> ephemeryNetwork = Optional.of(network);
+    final UInt64 invalidSlot = UInt64.valueOf(MAX_EPHEMERY_SLOT + 1);
+
+    assertThat(ephemeryNetwork).isPresent().contains(Eth2Network.EPHEMERY);
+    assertThatThrownBy(() -> ephemerySlotValidationService.onSlot(invalidSlot))
+        .isInstanceOf(IllegalStateException.class)
+        .hasMessageContaining(
+            String.format(
+                "Slot %s exceeds maximum allowed slot %s for ephemery network",
+                invalidSlot, MAX_EPHEMERY_SLOT));
+  }
+
+  @Test
+  public void onSlot_shouldNotThrowException_forNonEphemeryNetwork() {
+    final Eth2Network network = Eth2Network.SEPOLIA;
+    assertThat(network).isNotEqualTo(Eth2Network.EPHEMERY);
+    assertThatCode(() -> {}).doesNotThrowAnyException();
+  }
+
+  @Test
+  void shouldCompleteWhenServiceStartsAndStops() {
+    final SafeFuture<?> startFuture = ephemerySlotValidationService.doStart();
+    final SafeFuture<?> stopFuture = ephemerySlotValidationService.doStop();
+    assertTrue(startFuture.isDone());
+    assertTrue(stopFuture.isDone());
+  }
+}