SERVER-14872: Aggregation expression to concatenate multiple arrays into one

1 files changed, 39 insertions, 0 deletions

diff --git a/jstests/aggregation/bugs/server14872.js b/jstests/aggregation/bugs/server14872.js
new file mode 100644
index 00000000000..3be4018ac21
--- /dev/null
+++ b/jstests/aggregation/bugs/server14872.js
@@ -0,0 +1,39 @@
+// SERVER-14872: Aggregation expression to concatenate multiple arrays into one
+
+// For assertErrorCode.
+load('jstests/aggregation/extras/utils.js');
+
+(function() {
+    'use strict';
+
+    var coll = db.agg_concat_arrays_expr;
+    coll.drop();
+
+    assert.writeOK(coll.insert({a: [1, 2], b: ['three'], c: [], d: [[3], 4], e: null, str: 'x'}));
+
+    // Basic concatenation.
+    var pipeline = [{$project: {_id: 0, all: {$concatArrays: ['$a', '$b', '$c']}}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{all: [1, 2, 'three']}]);
+
+    // Concatenation with nested arrays.
+    pipeline = [{$project: {_id: 0, all: {$concatArrays: ['$a', '$d']}}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{all: [1, 2, [3], 4]}]);
+
+    // Concatenation with 1 argument.
+    pipeline = [{$project: {_id: 0, all: {$concatArrays: ['$a']}}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{all: [1, 2]}]);
+
+    // Concatenation with no arguments.
+    pipeline = [{$project: {_id: 0, all: {$concatArrays: []}}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{all: []}]);
+
+    // Any nullish inputs will result in null.
+    pipeline = [{$project: {_id: 0, all: {$concatArrays: ['$a', '$e']}}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{all: null}]);
+    pipeline = [{$project: {_id: 0, all: {$concatArrays: ['$a', '$f']}}}];
+    assert.eq(coll.aggregate(pipeline).toArray(), [{all: null}]);
+
+    // Error on any non-array, non-null inputs.
+    pipeline = [{$project: {_id: 0, all: {$concatArrays: ['$a', '$str']}}}];
+    assertErrorCode(coll, pipeline, 28664);
+}());