Fix types when combining measurements (#113686)

Author: mosche

test/framework/src/main/java/org/elasticsearch/telemetry/Measurement.java

@@ -52,10 +52,14 @@ public static List<Measurement> combine(List<Measurement> measurements) {
             if (m.isDouble != isDouble) {
                 throw new IllegalArgumentException("cannot combine measurements of different types");
             }
-            byAttr.compute(
-                m.attributes,
-                (k, v) -> (v == null) ? m.value : isDouble ? v.doubleValue() + m.getDouble() : v.longValue() + m.getLong()
-            );
+            byAttr.compute(m.attributes, (k, v) -> {
+                if (v == null) return m.value;
+                if (isDouble) {
+                    return v.doubleValue() + m.getDouble();
+                } else {
+                    return v.longValue() + m.getLong();
+                }
+            });
         });
         return byAttr.entrySet()
             .stream()

test/framework/src/test/java/org/elasticsearch/telemetry/MeasurementTests.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.telemetry;
+
+import org.elasticsearch.test.ESTestCase;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+import static org.hamcrest.Matchers.containsInAnyOrder;
+
+public class MeasurementTests extends ESTestCase {
+
+    public void testCombineLongs() {
+        Measurement m1 = new Measurement(1L, Collections.emptyMap(), false);
+        Measurement m2 = new Measurement(2L, Collections.emptyMap(), false);
+        Measurement m3 = new Measurement(3L, Map.of("k", "v"), false);
+        Measurement m4 = new Measurement(4L, Map.of("k", "v"), false);
+
+        List<Measurement> combined = Measurement.combine(List.of(m1, m2, m3, m4));
+        assertThat(
+            combined,
+            containsInAnyOrder(new Measurement(3L, Collections.emptyMap(), false), new Measurement(7L, Map.of("k", "v"), false))
+        );
+    }
+
+    public void testCombineDoubles() {
+        Measurement m1 = new Measurement(1.0, Collections.emptyMap(), true);
+        Measurement m2 = new Measurement(2.0, Collections.emptyMap(), true);
+        Measurement m3 = new Measurement(3.0, Map.of("k", "v"), true);
+        Measurement m4 = new Measurement(4.0, Map.of("k", "v"), true);
+
+        List<Measurement> combined = Measurement.combine(List.of(m1, m2, m3, m4));
+        assertThat(
+            combined,
+            containsInAnyOrder(new Measurement(3.0, Collections.emptyMap(), true), new Measurement(7.0, Map.of("k", "v"), true))
+        );
+    }
+
+}