SERVER-40526 Make agg Expressions walkable

1 files changed, 14 insertions, 1 deletions

diff --git a/src/mongo/db/pipeline/document_source_group_test.cpp b/src/mongo/db/pipeline/document_source_group_test.cpp
index 111a2db01f2..da25b97d397 100644
--- a/src/mongo/db/pipeline/document_source_group_test.cpp
+++ b/src/mongo/db/pipeline/document_source_group_test.cpp
@@ -207,7 +207,20 @@ TEST_F(DocumentSourceGroupTest, ShouldReportMultipleFieldGroupKeysAsARename) {
     VariablesParseState vps = expCtx->variablesParseState;
     auto x = ExpressionFieldPath::parse(expCtx, "$x", vps);
     auto y = ExpressionFieldPath::parse(expCtx, "$y", vps);
-    auto groupByExpression = ExpressionObject::create(expCtx, {{"x", x}, {"y", y}});
+    auto groupByExpression = [&]() {
+        std::vector<boost::intrusive_ptr<Expression>> children;
+        std::vector<std::pair<std::string, boost::intrusive_ptr<Expression>&>> expressions;
+        auto doc = std::vector<std::pair<std::string, boost::intrusive_ptr<Expression>>>{{"x", x},
+                                                                                         {"y", y}};
+        for (auto & [ unused, expression ] : doc)
+            children.push_back(std::move(expression));
+        std::vector<boost::intrusive_ptr<Expression>>::size_type index = 0;
+        for (auto & [ fieldName, unused ] : doc) {
+            expressions.emplace_back(fieldName, children[index]);
+            ++index;
+        }
+        return ExpressionObject::create(expCtx, std::move(children), std::move(expressions));
+    }();
     auto group = DocumentSourceGroup::create(expCtx, groupByExpression, {});
     auto modifiedPathsRet = group->getModifiedPaths();
     ASSERT(modifiedPathsRet.type == DocumentSource::GetModPathsReturn::Type::kAllExcept);