1 files changed, 77 insertions, 0 deletions
diff --git a/jstests/aggregation/bugs/window_inside_facet.js b/jstests/aggregation/bugs/window_inside_facet.js
new file mode 100644
index 00000000000..baf9fcd5150
--- /dev/null
+++ b/jstests/aggregation/bugs/window_inside_facet.js
@@ -0,0 +1,77 @@
+// Test that $setWindowFields inside $facet correctly propagates its state when it encounters paused
+// execution.
+(function() {
+"use strict";
+
+const coll = db.window_inside_facet;
+coll.drop();
+
+assert.commandWorked(coll.insert([
+    {_id: 'a', n: 0},
+    {_id: 'b', n: 1},
+    {_id: 'c', n: 2},
+    {_id: 'd', n: 3},
+    {_id: 'e', n: 4},
+    {_id: 'f', n: 5}
+]));
+
+// Test window with a sort within $facet alongside another pipeline that will cause it to pause
+// execution. The sort will cause the window to hit paused execution immediately, before an advance.
+let result =
+    coll.aggregate({
+            $facet: {
+                facet1: [{
+                    $setWindowFields: {
+                        output: {prevId: {$shift: {by: -1, default: null, output: "$_id"}}},
+                        sortBy: {_id: 1}
+                    }
+                }],
+                facet2: [{$count: "count"}]
+            }
+        })
+        .toArray()[0];
+let expected = {
+    facet1: [
+        {_id: 'a', n: 0, prevId: null},
+        {_id: 'b', n: 1, prevId: 'a'},
+        {_id: 'c', n: 2, prevId: 'b'},
+        {_id: 'd', n: 3, prevId: 'c'},
+        {_id: 'e', n: 4, prevId: 'd'},
+        {_id: 'f', n: 5, prevId: 'e'}
+    ],
+    facet2: [{count: 6}]
+};
+assert.docEq(expected, result, "$setWindowFields with sort failed.");
+
+// Test window with no sort within $facet alongside another pipeline that will cause it to pause
+// execution. Having no sort will cause the window to hit paused execution after advancing.
+result = coll.aggregate({
+                 $facet: {
+                     facet1: [
+                         {
+                             $setWindowFields: {
+                                 output: {
+                                     min: {$min: "$n"},
+                                     max: {$max: "$n"},
+                                 }
+                             }
+                         },
+                         {$sort: {_id: 1}}
+                     ],
+                     facet2: [{$count: "count"}]
+                 }
+             })
+             .toArray()[0];
+expected = {
+    facet1: [
+        {_id: 'a', n: 0, min: 0, max: 5},
+        {_id: 'b', n: 1, min: 0, max: 5},
+        {_id: 'c', n: 2, min: 0, max: 5},
+        {_id: 'd', n: 3, min: 0, max: 5},
+        {_id: 'e', n: 4, min: 0, max: 5},
+        {_id: 'f', n: 5, min: 0, max: 5}
+    ],
+    facet2: [{count: 6}]
+};
+assert.docEq(expected, result, "$setWindowFields without sort failed.");
+}());