Random fixes in currently unused test metrics code

2 files changed, 9 insertions, 2 deletions

diff --git a/tenant-cd/src/main/java/ai/vespa/hosted/cd/metric/Metric.java b/tenant-cd/src/main/java/ai/vespa/hosted/cd/metric/Metric.java
index cb3c8e77a9a..cc9d5d82b2c 100644
--- a/tenant-cd/src/main/java/ai/vespa/hosted/cd/metric/Metric.java
+++ b/tenant-cd/src/main/java/ai/vespa/hosted/cd/metric/Metric.java
@@ -7,6 +7,7 @@ import java.util.Set;
 import java.util.StringJoiner;
 
 import static java.util.Map.copyOf;
+import static java.util.stream.Collectors.reducing;
 import static java.util.stream.Collectors.toUnmodifiableMap;
 
 /**
@@ -58,7 +59,8 @@ public class Metric {
 
     /** Returns a collapsed version of this, with all statistics aggregated. This does not preserve last, 95 and 99 percentile values. */
     public Metric collapse() {
-        return collapse(statistics.keySet().iterator().next().keySet());
+        Map<String, ?> firstStatistic = statistics.keySet().iterator().next();
+        return firstStatistic == null ? this : collapse(firstStatistic.keySet());
     }
 
     /** If this Metric contains a single point, returns the Statistic of that point; otherwise, throws an exception. */
diff --git a/tenant-cd/src/main/java/ai/vespa/hosted/cd/metric/Statistic.java b/tenant-cd/src/main/java/ai/vespa/hosted/cd/metric/Statistic.java
index fc52900bdac..f1cb89641b3 100644
--- a/tenant-cd/src/main/java/ai/vespa/hosted/cd/metric/Statistic.java
+++ b/tenant-cd/src/main/java/ai/vespa/hosted/cd/metric/Statistic.java
@@ -1,6 +1,7 @@
 package ai.vespa.hosted.cd.metric;
 
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.StringJoiner;
@@ -22,6 +23,10 @@ public class Statistic {
     }
 
     public static Statistic of(Map<Type, Double> data) {
+        for (Type type : List.of(Type.count, Type.rate, Type.average))
+            if ( ! data.containsKey(type))
+                throw new IllegalArgumentException("Required data type '" + type + "' not present in '" + data + "'");
+
         return new Statistic(copyOf(data));
     }
 
@@ -40,7 +45,7 @@ public class Statistic {
 
     Statistic mergedWith(Statistic other) {
         if (data.keySet().equals(other.data.keySet()))
-            throw new IllegalArgumentException("Incompatible key sets '" + data.keySet() + "' and '" + other.data.keySet() + "'.");
+            throw new IllegalArgumentException("Unequal key sets '" + data.keySet() + "' and '" + other.data.keySet() + "'.");
 
         Map<Type, Double> merged = new HashMap<>();
         double n1 = get(Type.count), n2 = other.get(Type.count);