SERVER-40240 Add new $unset aggregation stage

1 files changed, 35 insertions, 0 deletions

diff --git a/jstests/aggregation/sources/unset/unset.js b/jstests/aggregation/sources/unset/unset.js
new file mode 100644
index 00000000000..70adb54db8d
--- /dev/null
+++ b/jstests/aggregation/sources/unset/unset.js
@@ -0,0 +1,35 @@
+// Basic testing for the $unset aggregation stage.
+(function() {
+    "use strict";
+
+    load("jstests/aggregation/extras/utils.js");  // For assertArrayEq.
+
+    const coll = db.agg_stage_unset;
+    coll.drop();
+
+    assert.commandWorked(coll.insert(
+        [{_id: 0, a: 10}, {_id: 1, a: {b: 20, c: 30, 0: 40}}, {_id: 2, a: [{b: 50, c: 60}]}]));
+
+    // unset single field.
+    let result = coll.aggregate([{$unset: ["a"]}]).toArray();
+    assertArrayEq({actual: result, expected: [{_id: 0}, {_id: 1}, {_id: 2}]});
+
+    // unset multiple fields.
+    result = coll.aggregate([{$unset: ["_id", "a"]}]).toArray();
+    assertArrayEq({actual: result, expected: [{}, {}, {}]});
+
+    // unset with dotted field path.
+    result = coll.aggregate([{$unset: ["a.b"]}]).toArray();
+    assertArrayEq({
+        actual: result,
+        expected: [{_id: 0, a: 10}, {_id: 1, a: {0: 40, c: 30}}, {_id: 2, a: [{c: 60}]}]
+    });
+
+    // Numeric field paths in aggregation represent field name only and not array offset.
+    result = coll.aggregate([{$unset: ["a.0"]}]).toArray();
+    assertArrayEq({
+        actual: result,
+        expected: [{_id: 0, a: 10}, {_id: 1, a: {b: 20, c: 30}}, {_id: 2, a: [{b: 50, c: 60}]}]
+    });
+
+})();