Test default value of bound function "length" property

test/built-ins/Function/prototype/bind/instance-length-default-value.js

@@ -0,0 +1,52 @@
+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-function.prototype.bind
+description: >
+  "length" value of a bound function defaults to 0.
+  Non-own and non-number "length" values of target function are ignored.
+info: |
+  Function.prototype.bind ( thisArg, ...args )
+
+  [...]
+  5. Let targetHasLength be ? HasOwnProperty(Target, "length").
+  6. If targetHasLength is true, then
+    a. Let targetLen be ? Get(Target, "length").
+    b. If Type(targetLen) is not Number, let L be 0.
+    c. Else,
+      i. Set targetLen to ! ToInteger(targetLen).
+      ii. Let L be the larger of 0 and the result of targetLen minus the number of elements of args.
+  7. Else, let L be 0.
+  8. Perform ! SetFunctionLength(F, L).
+  [...]
+features: [Symbol]
+---*/
+
+function foo() {}
+
+Object.defineProperty(foo, "length", {value: undefined});
+assert.sameValue(foo.bind(null, 1).length, 0, "undefined");
+
+Object.defineProperty(foo, "length", {value: null});
+assert.sameValue(foo.bind(null, 1).length, 0, "null");
+
+Object.defineProperty(foo, "length", {value: true});
+assert.sameValue(foo.bind(null, 1).length, 0, "boolean");
+
+Object.defineProperty(foo, "length", {value: "1"});
+assert.sameValue(foo.bind(null, 1).length, 0, "string");
+
+Object.defineProperty(foo, "length", {value: Symbol("1")});
+assert.sameValue(foo.bind(null, 1).length, 0, "symbol");
+
+Object.defineProperty(foo, "length", {value: new Number(1)});
+assert.sameValue(foo.bind(null, 1).length, 0, "Number object");
+
+
+function bar() {}
+Object.setPrototypeOf(bar, {length: 42});
+assert(delete bar.length);
+
+var bound = Function.prototype.bind.call(bar, null, 1);
+assert.sameValue(bound.length, 0, "not own");