1 files changed, 43 insertions, 0 deletions
diff --git a/jstests/core/index/wildcard/wildcard_index_empty_arrays.js b/jstests/core/index/wildcard/wildcard_index_empty_arrays.js
new file mode 100644
index 00000000000..b1188594621
--- /dev/null
+++ b/jstests/core/index/wildcard/wildcard_index_empty_arrays.js
@@ -0,0 +1,43 @@
+/**
+ * Tests that wildcard indexes will correctly match for empty arrays.
+ */
+(function() {
+"use strict";
+
+load("jstests/aggregation/extras/utils.js");  // For arrayEq.
+
+const coll = db.wildcard_empty_arrays;
+coll.drop();
+
+const assertArrayEq = (l, r) => assert(arrayEq(l, r), tojson(l) + " != " + tojson(r));
+
+const indexWildcard = {
+    "$**": 1
+};
+assert.commandWorked(coll.createIndex(indexWildcard));
+
+assert.commandWorked(coll.insert({a: 1, b: 1, c: [], d: {e: [5, 6]}}));
+assert.commandWorked(coll.insert({a: 2, b: 2, c: [1, 2], d: {e: []}}));
+assert.commandWorked(coll.insert({a: 1, b: 2, c: [3, 4], d: {e: [7, 8]}, f: [{g: []}]}));
+assert.commandWorked(coll.insert({a: 2, b: [[]], c: 1, d: 4}));
+
+// $** index matches empty array.
+assertArrayEq(coll.find({c: []}, {_id: 0}).hint(indexWildcard).toArray(),
+              [{a: 1, b: 1, c: [], d: {e: [5, 6]}}]);
+
+// $** index supports equality to array offset.
+assertArrayEq(coll.find({"c.0": 1}, {_id: 0}).hint(indexWildcard).toArray(),
+              [{a: 2, b: 2, c: [1, 2], d: {e: []}}]);
+
+// $** index matches empty array nested in object.
+assertArrayEq(coll.find({"d.e": []}, {_id: 0}).hint(indexWildcard).toArray(),
+              [{a: 2, b: 2, c: [1, 2], d: {e: []}}]);
+
+// $** index matches empty array nested within an array of objects.
+assertArrayEq(coll.find({"f.0.g": []}, {_id: 0}).hint(indexWildcard).toArray(),
+              [{a: 1, b: 2, c: [3, 4], d: {e: [7, 8]}, f: [{g: []}]}]);
+
+// $** index matches empty array nested within an array.
+assertArrayEq(coll.find({"b": []}, {_id: 0}).hint(indexWildcard).toArray(),
+              [{a: 2, b: [[]], c: 1, d: 4}]);
+})();