1 files changed, 23 insertions, 0 deletions
diff --git a/container-core/src/test/java/com/yahoo/container/jdisc/state/MetricSnapshotTest.java b/container-core/src/test/java/com/yahoo/container/jdisc/state/MetricSnapshotTest.java
new file mode 100644
index 00000000000..9dc9379e585
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+++ b/container-core/src/test/java/com/yahoo/container/jdisc/state/MetricSnapshotTest.java
@@ -0,0 +1,23 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.container.jdisc.state;
+
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class MetricSnapshotTest {
+    /**
+     * Aggregate metrics are not cloned into new snapshot. In turn, a metric
+     * set with only aggregates will be added as an empty set if we do not
+     * filter these away at clone time. This test ensures that we do just that.
+     * If/when we start carrying aggregates across snapshots, this test will
+     * most likely be deprecated.
+     */
+    @Test
+    public void emptyMetricSetNotAddedToClonedSnapshot() {
+        final StateMetricContext ctx = StateMetricContext.newInstance(null);
+        MetricSnapshot snapshot = new MetricSnapshot();
+        snapshot.add(ctx, "foo", 1234);
+        MetricSnapshot newSnapshot = snapshot.createSnapshot();
+        assertFalse(newSnapshot.iterator().hasNext());
+    }
+}