diff --git a/src/test/java/com/googlesource/gerrit/plugins/multisite/consumer/SubscriberMetricsTest.java b/src/test/java/com/googlesource/gerrit/plugins/multisite/consumer/SubscriberMetricsTest.java
new file mode 100644
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+++ b/src/test/java/com/googlesource/gerrit/plugins/multisite/consumer/SubscriberMetricsTest.java
@@ -0,0 +1,98 @@
+// Copyright (C) 2020 The Android Open Source Project
+//
+// 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 com.googlesource.gerrit.plugins.multisite.consumer;
+
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import com.gerritforge.gerrit.eventbroker.EventMessage;
+import com.google.common.base.Suppliers;
+import com.google.gerrit.metrics.MetricMaker;
+import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.server.data.RefUpdateAttribute;
+import com.google.gerrit.server.events.RefUpdatedEvent;
+import com.google.gerrit.server.extensions.events.GitReferenceUpdated;
+import com.googlesource.gerrit.plugins.multisite.ProjectVersionLogger;
+import com.googlesource.gerrit.plugins.multisite.SharedRefDatabaseWrapper;
+import com.googlesource.gerrit.plugins.multisite.validation.ProjectVersionRefUpdate;
+import java.util.Optional;
+import java.util.UUID;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+
+@RunWith(MockitoJUnitRunner.class)
+public class SubscriberMetricsTest {
+  private static final String A_TEST_PROJECT_NAME = "test-project";
+  private static final Project.NameKey A_TEST_PROJECT_NAME_KEY =
+      Project.nameKey(A_TEST_PROJECT_NAME);
+
+  @Mock private SharedRefDatabaseWrapper sharedRefDb;
+  @Mock private GitReferenceUpdated gitReferenceUpdated;
+  @Mock private MetricMaker metricMaker;
+  @Mock private ProjectVersionLogger verLogger;
+  @Mock private ProjectVersionRefUpdate projectVersionRefUpdate;
+  private SubscriberMetrics metrics;
+  private EventMessage.Header msgHeader;
+
+  @Before
+  public void setup() throws Exception {
+    msgHeader = new EventMessage.Header(UUID.randomUUID(), UUID.randomUUID());
+    metrics = new SubscriberMetrics(metricMaker, projectVersionRefUpdate, verLogger);
+  }
+
+  @Test
+  public void shouldLogProjectVersionWhenReceivingRefUpdatedEventWithoutLag() {
+    Optional<Long> globalRefDbVersion = Optional.of(System.currentTimeMillis() / 1000);
+    when(projectVersionRefUpdate.getProjectRemoteVersion(A_TEST_PROJECT_NAME))
+        .thenReturn(globalRefDbVersion);
+    when(projectVersionRefUpdate.getProjectLocalVersion(A_TEST_PROJECT_NAME))
+        .thenReturn(globalRefDbVersion);
+
+    EventMessage eventMessage = new EventMessage(msgHeader, newRefUpdateEvent());
+
+    metrics.updateReplicationStatusMetrics(eventMessage);
+
+    verify(verLogger).log(A_TEST_PROJECT_NAME_KEY, globalRefDbVersion.get(), 0);
+  }
+
+  @Test
+  public void shouldLogProjectVersionWhenReceivingRefUpdatedEventWithALag() {
+    Optional<Long> globalRefDbVersion = Optional.of(System.currentTimeMillis() / 1000);
+    long replicationLag = 60;
+    when(projectVersionRefUpdate.getProjectRemoteVersion(A_TEST_PROJECT_NAME))
+        .thenReturn(globalRefDbVersion.map(ts -> ts + replicationLag));
+    when(projectVersionRefUpdate.getProjectLocalVersion(A_TEST_PROJECT_NAME))
+        .thenReturn(globalRefDbVersion);
+
+    EventMessage eventMessage = new EventMessage(msgHeader, newRefUpdateEvent());
+
+    metrics.updateReplicationStatusMetrics(eventMessage);
+
+    verify(verLogger).log(A_TEST_PROJECT_NAME_KEY, globalRefDbVersion.get(), replicationLag);
+  }
+
+  private RefUpdatedEvent newRefUpdateEvent() {
+    RefUpdateAttribute refUpdate = new RefUpdateAttribute();
+    refUpdate.project = A_TEST_PROJECT_NAME;
+    refUpdate.refName = "refs/heads/foo";
+    refUpdate.newRev = "591727cfec5174368a7829f79741c41683d84c89";
+    RefUpdatedEvent refUpdateEvent = new RefUpdatedEvent();
+    refUpdateEvent.refUpdate = Suppliers.ofInstance(refUpdate);
+    return refUpdateEvent;
+  }
+}