SERVER-38362 Prevent $out stage within $lookup

1 files changed, 72 insertions, 0 deletions

diff --git a/jstests/aggregation/sources/out/out_in_lookup_not_allowed.js b/jstests/aggregation/sources/out/out_in_lookup_not_allowed.js
new file mode 100644
index 00000000000..e709fbce1d3
--- /dev/null
+++ b/jstests/aggregation/sources/out/out_in_lookup_not_allowed.js
@@ -0,0 +1,72 @@
+// Tests that $out cannot be used within a $lookup pipeline.
+(function() {
+    "use strict";
+
+    load("jstests/aggregation/extras/utils.js");       // For assertErrorCode.
+    load("jstests/libs/collection_drop_recreate.js");  // For assertDropCollection.
+
+    const ERROR_CODE_OUT_BANNED_IN_LOOKUP = 51047;
+    const ERROR_CODE_OUT_LAST_STAGE_ONLY = 40601;
+    const coll = db.out_in_lookup_not_allowed;
+    coll.drop();
+
+    const from = db.out_in_lookup_not_allowed_from;
+    from.drop();
+
+    let pipeline = [
+        {
+          $lookup: {
+              pipeline: [{$out: "out_collection"}],
+              from: from.getName(),
+              as: "c",
+          }
+        },
+    ];
+
+    assertErrorCode(coll, pipeline, ERROR_CODE_OUT_BANNED_IN_LOOKUP);
+
+    pipeline = [
+        {
+          $lookup: {
+              pipeline: [{$project: {x: 0}}, {$out: "out_collection"}],
+              from: from.getName(),
+              as: "c",
+          }
+        },
+    ];
+
+    assertErrorCode(coll, pipeline, ERROR_CODE_OUT_BANNED_IN_LOOKUP);
+
+    pipeline = [
+        {
+          $lookup: {
+              pipeline: [{$out: "out_collection"}, {$match: {x: true}}],
+              from: from.getName(),
+              as: "c",
+          }
+        },
+    ];
+
+    // Pipeline will fail because $out is not last in the subpipeline.
+    // Validation for $out in a $lookup's subpipeline occurs at a later point.
+    assertErrorCode(coll, pipeline, ERROR_CODE_OUT_LAST_STAGE_ONLY);
+
+    // Create view which contains $out within $lookup.
+    assertDropCollection(coll.getDB(), "view1");
+
+    pipeline = [
+        {
+          $lookup: {
+              pipeline: [{$out: "out_collection"}],
+              from: from.getName(),
+              as: "c",
+          }
+        },
+    ];
+
+    // Pipeline will fail because $out is not allowed to exist within a $lookup.
+    // Validation for $out in a view occurs at a later point.
+    const cmdRes =
+        coll.getDB().runCommand({create: "view1", viewOn: coll.getName(), pipeline: pipeline});
+    assert.commandFailedWithCode(cmdRes, ERROR_CODE_OUT_BANNED_IN_LOOKUP);
+}());