SERVER-8141 Avoid treating arrays as literals in aggregation pipeline

1 files changed, 48 insertions, 0 deletions

diff --git a/jstests/aggregation/bugs/server8141.js b/jstests/aggregation/bugs/server8141.js
new file mode 100644
index 00000000000..d450ec14227
--- /dev/null
+++ b/jstests/aggregation/bugs/server8141.js
@@ -0,0 +1,48 @@
+// SERVER-8141 Avoid treating arrays as literals in aggregation pipeline.
+(function() {
+    'use strict';
+    var coll = db.exprs_in_arrays;
+    coll.drop();
+
+    assert.writeOK(coll.insert({_id: 0, a: ['foo', 'bar', 'baz'], b: 'bar', c: 'Baz'}));
+
+    // An array of constants should still evaluate to an array of constants.
+    var pipeline = [{$project: {_id: 0, d: ['constant', 1]}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{d: ['constant', 1]}]);
+
+    // A field name inside an array should take on the value of that field.
+    pipeline = [{$project: {_id: 0, d: ['$b']}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{d: ['bar']}]);
+
+    // An expression inside an array should be evaluated.
+    pipeline = [{$project: {_id: 0, d: [{$toLower: 'FoO'}]}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{d: ['foo']}]);
+
+    // Both an expression and a field name inside an array should be evaluated.
+    pipeline = [{$project: {_id: 0, d: ['$b', {$toLower: 'FoO'}]}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{d: ['bar', 'foo']}]);
+
+    // A nested array should still be evaluated.
+    pipeline = [{$project: {_id: 0, d: ['$b', 'constant', [1, {$toLower: 'FoO'}]]}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{d: ['bar', 'constant', [1, 'foo']]}]);
+
+    // Should still evaluate array elements inside arguments to an expression.
+    pipeline = [{$project: {_id: 0, d: {$setIntersection: ['$a', ['$b']]}}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{d: ['bar']}]);
+
+    pipeline = [{$project: {_id: 0, d: {$setIntersection: ['$a', [{$toLower: 'FoO'}]]}}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{d: ['foo']}]);
+
+    // Nested arrays.
+    pipeline = [{$project: {_id: 0, d: {$setIntersection: [[[1, 'foo', 'bar']],
+                                                           [[1, {$toLower: 'FoO'}, '$b']]]}}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{d: [[1, 'foo', 'bar']]}]);
+
+    coll.drop();
+
+    // Should replace missing values with NULL to preserve indices.
+    assert.writeOK(coll.insert({_id: 1, x: 1, z: 2}));
+
+    pipeline = [{$project: {_id: 0, coordinate: ['$x', '$y', '$z']}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{coordinate: [1, null, 2]}]);
+}());