new test

Author: fandreuz

sdk/metrics/src/test/java/io/opentelemetry/sdk/metrics/internal/aggregator/DoubleLastValueAggregatorTest.java

@@ -6,6 +6,7 @@
 package io.opentelemetry.sdk.metrics.internal.aggregator;
 
 import static io.opentelemetry.sdk.testing.assertj.OpenTelemetryAssertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 import io.opentelemetry.api.common.AttributeKey;
 import io.opentelemetry.api.common.Attributes;
@@ -276,4 +277,13 @@ void testReusableDataOnCollect() {
 
     assertThat(pointData).isSameAs(pointDataWithReset);
   }
+
+  @Test
+  void testNullPointerExceptionWhenUnset() {
+    init(MemoryMode.REUSABLE_DATA);
+    AggregatorHandle<DoublePointData, DoubleExemplarData> handle = aggregator.createHandle();
+    assertThatThrownBy(
+            () -> handle.aggregateThenMaybeReset(0, 10, Attributes.empty(), /* reset= */ true))
+        .isInstanceOf(NullPointerException.class);
+  }
 }