SERVER-47893 Add test confirming that variables defined above a $graphLookup are available for use

(cherry picked from commit b60db3513af2905e0bf4aa9865364d07a46ac4b8)
(cherry picked from commit 54c4f1a963c220eacf7ed7cb6a052affcb954725)

1 files changed, 24 insertions, 0 deletions

diff --git a/jstests/aggregation/sources/graphLookup/filter.js b/jstests/aggregation/sources/graphLookup/filter.js
index 4b46c843d9a..da828cb66c7 100644
--- a/jstests/aggregation/sources/graphLookup/filter.js
+++ b/jstests/aggregation/sources/graphLookup/filter.js
@@ -91,4 +91,28 @@ res = local
               .toArray()[0];
 
 assert.eq(res.results.length, 1);
+
+// $expr within `restrictSearchWithMatch` has access to variables declared at a higher level.
+res = local
+                .aggregate([{
+                    $lookup: {
+                        from: "local",
+                        let : {foo: true},
+                        pipeline: [{
+                            $graphLookup: {
+                                from: "foreign",
+                                startWith: "$starting",
+                                connectFromField: "to",
+                                connectToField: "from",
+                                as: "results",
+                                restrictSearchWithMatch:
+                                    {$expr: {$eq: ["$shouldBeIncluded", "$$foo"]}}
+                            }
+                        }],
+                        as: "array"
+                    }
+                }])
+                .toArray()[0];
+
+assert.eq(res.array[0].results.length, 1);
 })();