Metrics: Copy TimeSeries list when creating a Metric. (#1485)

* Metrics: Copy TimeSeries list when creating a Metric.

* Check for null and add more tests.

2 files changed, 38 insertions, 1 deletions

diff --git a/api/src/main/java/io/opencensus/metrics/export/Metric.java b/api/src/main/java/io/opencensus/metrics/export/Metric.java
index 07fe356a..5e2fa5e8 100644
--- a/api/src/main/java/io/opencensus/metrics/export/Metric.java
+++ b/api/src/main/java/io/opencensus/metrics/export/Metric.java
@@ -23,6 +23,8 @@ import io.opencensus.metrics.export.Value.ValueDistribution;
 import io.opencensus.metrics.export.Value.ValueDouble;
 import io.opencensus.metrics.export.Value.ValueLong;
 import io.opencensus.metrics.export.Value.ValueSummary;
+import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import javax.annotation.concurrent.Immutable;
 
@@ -47,8 +49,12 @@ public abstract class Metric {
    * @since 0.17
    */
   public static Metric create(MetricDescriptor metricDescriptor, List<TimeSeries> timeSeriesList) {
+    Utils.checkNotNull(metricDescriptor, "metricDescriptor");
+    Utils.checkNotNull(timeSeriesList, "timeSeriesList");
+    Utils.checkListElementNotNull(timeSeriesList, "timeSeries");
     checkTypeMatch(metricDescriptor.getType(), timeSeriesList);
-    return new AutoValue_Metric(metricDescriptor, timeSeriesList);
+    return new AutoValue_Metric(
+        metricDescriptor, Collections.unmodifiableList(new ArrayList<TimeSeries>(timeSeriesList)));
   }
 
   /**
diff --git a/api/src/test/java/io/opencensus/metrics/export/MetricTest.java b/api/src/test/java/io/opencensus/metrics/export/MetricTest.java
index 0b1ecf65..52fa2c47 100644
--- a/api/src/test/java/io/opencensus/metrics/export/MetricTest.java
+++ b/api/src/test/java/io/opencensus/metrics/export/MetricTest.java
@@ -23,6 +23,7 @@ import io.opencensus.common.Timestamp;
 import io.opencensus.metrics.LabelKey;
 import io.opencensus.metrics.LabelValue;
 import io.opencensus.metrics.export.MetricDescriptor.Type;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
@@ -103,6 +104,36 @@ public class MetricTest {
   }
 
   @Test
+  public void create_WithNullMetricDescriptor() {
+    thrown.expect(NullPointerException.class);
+    thrown.expectMessage("metricDescriptor");
+    Metric.create(null, Collections.<TimeSeries>emptyList());
+  }
+
+  @Test
+  public void create_WithNullTimeSeriesList() {
+    thrown.expect(NullPointerException.class);
+    thrown.expectMessage("timeSeriesList");
+    Metric.create(METRIC_DESCRIPTOR_1, null);
+  }
+
+  @Test
+  public void create_WithNullTimeSeries() {
+    thrown.expect(NullPointerException.class);
+    thrown.expectMessage("timeSeries");
+    Metric.create(METRIC_DESCRIPTOR_1, Arrays.asList(GAUGE_TIME_SERIES_1, null));
+  }
+
+  @Test
+  public void immutableTimeSeriesList() {
+    List<TimeSeries> timeSeriesList = new ArrayList<TimeSeries>();
+    timeSeriesList.add(GAUGE_TIME_SERIES_1);
+    Metric metric = Metric.create(METRIC_DESCRIPTOR_1, timeSeriesList);
+    timeSeriesList.add(GAUGE_TIME_SERIES_2);
+    assertThat(metric.getTimeSeriesList()).containsExactly(GAUGE_TIME_SERIES_1);
+  }
+
+  @Test
   public void testEquals() {
     new EqualsTester()
         .addEqualityGroup(