SERVER-57164 isVariableReference includes system variables

This fixes an invariant failure in DocumentSourceGroup.

1 files changed, 27 insertions, 0 deletions

diff --git a/jstests/aggregation/sources/group/group_by_system_variable.js b/jstests/aggregation/sources/group/group_by_system_variable.js
new file mode 100644
index 00000000000..6c223343166
--- /dev/null
+++ b/jstests/aggregation/sources/group/group_by_system_variable.js
@@ -0,0 +1,27 @@
+/*
+ * Tests that the server doesn't crash when you group by a system variable.
+ * Reproduces SERVER-57164.
+ */
+(function() {
+"use strict";
+
+const coll = db.group_by_system_variable;
+coll.drop();
+assert.commandWorked(coll.insert({}));
+
+// These explains all should not throw.
+coll.explain().aggregate({$group: {_id: "$$IS_MR"}});
+coll.explain().aggregate({$group: {_id: "$$JS_SCOPE"}});
+coll.explain().aggregate({$group: {_id: "$$CLUSTER_TIME"}});
+
+// These queries throw, but the server should stay up.
+assert.throws(() => coll.aggregate({$group: {_id: "$$IS_MR"}}));
+assert.throws(() => coll.aggregate({$group: {_id: "$$JS_SCOPE"}}));
+try {
+    // This one may or may not throw: CLUSTER_TIME may or may not be defined,
+    // depending on what kind of cluster we're running against.
+    coll.aggregate({$group: {_id: "$$CLUSTER_TIME"}});
+} catch (e) {
+}
+db.hello();
+})();