Proof-of-Pass Receipt — M-011

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 74bd4a5..da34780 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -37,6 +37,7 @@ This release marks our first release under the Prometheus umbrella.
 - AggregatorRegistry renamed to ClusterRegistry, old name deprecated
 - chore: update faceoff to 1.1
 - perf: Stat aggregation uses similar strategy to collection. 60% faster aggregation
+- Make cluster metric aggregation independent of worker response order
 
 ### Added
 
diff --git a/lib/metricAggregators.js b/lib/metricAggregators.js
index 8ea0528..6c2a1dd 100644
--- a/lib/metricAggregators.js
+++ b/lib/metricAggregators.js
@@ -51,6 +51,13 @@ function AggregatorFactory(aggregatorFn) {
 // Export for users to define their own aggregation methods.
 exports.AggregatorFactory = AggregatorFactory;
 
+function sumValues(values) {
+	return values
+		.slice()
+		.sort((a, b) => a.value - b.value)
+		.reduce((p, c) => p + c.value, 0);
+}
+
 /**
  * Functions that can be used to aggregate metrics from multiple registries.
  */
@@ -58,7 +65,7 @@ exports.aggregators = {
 	/**
 	 * @returns The sum of values.
 	 */
-	sum: AggregatorFactory(v => v.reduce((p, c) => p + c.value, 0)),
+	sum: AggregatorFactory(sumValues),
 	/**
 	 * @returns The first value.
 	 */
@@ -70,9 +77,7 @@ exports.aggregators = {
 	/**
 	 * @returns The arithmetic mean of the values.
 	 */
-	average: AggregatorFactory(
-		v => v.reduce((p, c) => p + c.value, 0) / v.length,
-	),
+	average: AggregatorFactory(v => sumValues(v) / v.length),
 	/**
 	 * @returns The minimum of the values.
 	 */
diff --git a/test/aggregatorsTest.js b/test/aggregatorsTest.js
index 0010a65..f3f77ad 100644
--- a/test/aggregatorsTest.js
+++ b/test/aggregatorsTest.js
@@ -34,6 +34,20 @@ describe('aggregators', () => {
 				{ value: 6, labels: ['label1'] },
 			]);
 		});
+
+		it('sums values independently of their order', () => {
+			const workerMetrics = [0.1, 0.2, 0.3].map(value => ({
+				help: 'metric_help',
+				name: 'metric_name',
+				type: 'does not matter',
+				values: [{ labels: [], value }],
+			}));
+
+			const result = aggregators.sum(workerMetrics);
+			const reorderedResult = aggregators.sum(workerMetrics.slice().reverse());
+
+			expect(result.values[0].value).toBe(reorderedResult.values[0].value);
+		});
 	});
 
 	describe('first', () => {