SERVER-14466 test use of DBRef fields in aggregation and find() expressions

2 files changed, 53 insertions, 2 deletions

diff --git a/jstests/core/elemMatchProjection.js b/jstests/core/elemMatchProjection.js
index 1e6632ea2a5..1bf4fe11217 100644
--- a/jstests/core/elemMatchProjection.js
+++ b/jstests/core/elemMatchProjection.js
@@ -1,5 +1,4 @@
-// @tags: [requires_getmore]
-
+// @tags: [requires_getmore, requires_fcv_44]
 // Tests for $elemMatch projections and $ positional operator projection.
 (function() {
 "use strict";
@@ -65,6 +64,18 @@ for (let i = 0; i < 100; i++) {
     bulk.insert({_id: nextId(), group: 12, x: {y: [{a: 1, b: 1}, {a: 1, b: 2}]}});
     bulk.insert({_id: nextId(), group: 13, x: [{a: 1, b: 1}, {a: 1, b: 2}]});
     bulk.insert({_id: nextId(), group: 13, x: [{a: 1, b: 2}, {a: 1, b: 1}]});
+
+    // Array of DBRefs. Don't actually try to dereference them, though, as they point to
+    // non-existing collections.
+    bulk.insert({
+        _id: nextId(),
+        group: 14,
+        x: [
+            new DBRef("otherCollection", "id0", db.getName()),
+            new DBRef("otherCollection", "id1", db.getName()),
+            new DBRef("otherCollection2", "id2", db.getName())
+        ]
+    });
 }
 assert.commandWorked(bulk.execute());
 
@@ -217,6 +228,16 @@ assert.eq({"x": [{"a": 1, "b": 2}], "y": [{"c": 3, "d": 4}]},
               .toArray()[0],
           "multiple $elemMatch on unique fields 1");
 
+// Perform a $elemMatch on a DBRef field.
+assert.eq(coll.find({group: 14}, {x: {$elemMatch: {$id: "id0"}}}).toArray()[0].x,
+          [new DBRef("otherCollection", "id0", db.getName())]);
+
+assert.eq(coll.find({group: 14}, {x: {$elemMatch: {$ref: "otherCollection2"}}}).toArray()[0].x,
+          [new DBRef("otherCollection2", "id2", db.getName())]);
+
+assert.eq(coll.find({group: 14}, {x: {$elemMatch: {$db: db.getName()}}}).toArray()[0].x,
+          [new DBRef("otherCollection", "id0", db.getName())]);
+
 // Tests involving getMore. Test the $-positional operator across multiple batches.
 let a = coll.find({group: 3, 'x.b': 2}, {'x.$': 1}).sort({_id: 1}).batchSize(1);
 while (a.hasNext()) {
diff --git a/jstests/core/views/dbref_projection.js b/jstests/core/views/dbref_projection.js
new file mode 100644
index 00000000000..963a3cc185e
--- /dev/null
+++ b/jstests/core/views/dbref_projection.js
@@ -0,0 +1,30 @@
+/**
+ * Test projecting DBRef fields ($ref, $id, $db) in views.
+ *
+ * Legacy find() queries do not support views, so must use the find() command.
+ * DBRef fields are not supported in agg pre 4.4.
+ * @tags: [requires_find_command, requires_fcv_44]
+ */
+(function() {
+"use strict";
+
+const viewsDB = db.getSiblingDB("views_dbref_projection");
+assert.commandWorked(viewsDB.dropDatabase());
+
+assert.commandWorked(
+    viewsDB.baseColl.insert({_id: 0, link: new DBRef("otherColl", "someId", viewsDB.getName())}));
+
+assert.commandWorked(viewsDB.runCommand({create: "view", viewOn: "baseColl"}));
+
+// Check that the view and base collection return the same thing.
+function checkViewAndBaseCollection(projection, expectedResult) {
+    const baseRes = viewsDB.baseColl.find({}, projection).toArray();
+    const viewRes = viewsDB.view.find({}, projection).toArray();
+    assert.eq(baseRes, viewRes);
+    assert.eq(expectedResult, baseRes);
+}
+
+checkViewAndBaseCollection({"link.$ref": 1}, [{_id: 0, link: {$ref: "otherColl"}}]);
+checkViewAndBaseCollection({"link.$db": 1}, [{_id: 0, link: {$db: viewsDB.getName()}}]);
+checkViewAndBaseCollection({"link.$id": 1}, [{_id: 0, link: {$id: "someId"}}]);
+}());