1 files changed, 24 insertions, 0 deletions
diff --git a/js/src/tests/test262/language/optional-chaining/update-expression-prefix.js b/js/src/tests/test262/language/optional-chaining/update-expression-prefix.js
new file mode 100644
index 0000000000..ba65aadc0c
--- /dev/null
+++ b/js/src/tests/test262/language/optional-chaining/update-expression-prefix.js
@@ -0,0 +1,24 @@
+// |reftest| error:SyntaxError
+// Copyright 2019 Google, Inc.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: prod-OptionalExpression
+description: >
+  optional chaining is forbidden in write contexts
+info: |
+  UpdateExpression[Yield, Await]:
+    LeftHandSideExpression++
+    LeftHandSideExpression--
+    ++UnaryExpression
+    --UnaryExpression
+features: [optional-chaining]
+negative:
+  phase: parse
+  type: SyntaxError
+---*/
+
+$DONOTEVALUATE();
+
+// --UnaryExpression
+const a = {};
+--a?.b;