1 files changed, 47 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/AsyncGeneratorFunction/instance-length.js b/js/src/tests/test262/built-ins/AsyncGeneratorFunction/instance-length.js
new file mode 100644
index 0000000000..c5de2941b7
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+++ b/js/src/tests/test262/built-ins/AsyncGeneratorFunction/instance-length.js
@@ -0,0 +1,47 @@
+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-asyncgeneratorfunction
+description: Definition of instance `length` property
+info: |
+    AsyncGeneratorFunction ( p1, p2, … , pn, body )
+    ...
+    3. Return CreateDynamicFunction(C, NewTarget, "async generator", args).
+
+    Runtime Semantics: CreateDynamicFunction
+    ...
+    // the parameter "args" is sliced into "parameters" and "body"
+    26. Perform FunctionInitialize(F, Normal, parameters, body, scope).
+    ...
+
+    FunctionInitialize
+    ...
+    2. Let len be the ExpectedArgumentCount of ParameterList.
+    3. Perform ! DefinePropertyOrThrow(F, "length",
+       PropertyDescriptor{[[Value]]: len, [[Writable]]: false, [[Enumerable]]:
+       false, [[Configurable]]: true}).
+    ...
+includes: [propertyHelper.js]
+features: [async-iteration]
+---*/
+
+var AsyncGeneratorFunction = Object.getPrototypeOf(async function* () {}).constructor;
+
+var instance = AsyncGeneratorFunction()
+
+verifyProperty(AsyncGeneratorFunction(), "length", {
+  value: 0,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+assert.sameValue(AsyncGeneratorFunction('').length, 0, "test 1");
+assert.sameValue(AsyncGeneratorFunction('x').length, 0, "test 2");
+assert.sameValue(AsyncGeneratorFunction('x', '').length, 1, "test 3");
+assert.sameValue(AsyncGeneratorFunction('x', 'y', '').length, 2, "test 4");
+assert.sameValue(AsyncGeneratorFunction('x, y', '').length, 2, "test 5");
+
+
+
+reportCompare(0, 0);