SERVER-57091 Fix infinite loop in GranularityRounderPreferredNumbers::roundDown

1 files changed, 22 insertions, 0 deletions

diff --git a/jstests/aggregation/sources/bucketauto/granularity_near_zero.js b/jstests/aggregation/sources/bucketauto/granularity_near_zero.js
new file mode 100644
index 00000000000..7f456f9428d
--- /dev/null
+++ b/jstests/aggregation/sources/bucketauto/granularity_near_zero.js
@@ -0,0 +1,22 @@
+// Tests when the granularity rounder needs to approach zero to round correctly. This test was
+// designed to reproduce SERVER-57091.
+(function() {
+"use strict";
+const coll = db.server57091;
+coll.drop();
+coll.insertOne({});
+
+const res =
+    coll.aggregate([{
+            $bucketAuto: {
+                groupBy: {
+                    $reduce:
+                        {input: [], initialValue: 4.940656484124654e-324, in : {$size: ["$$value"]}}
+                },
+                buckets: NumberLong("8"),
+                granularity: "R80"
+            }
+        }])
+        .toArray();
+assert.eq(res, [{_id: {min: 0, max: 1.02e-321}, count: 1}]);
+})();