v8/test/mjsunit/regress/regress-115452.js

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// Test that a function declaration cannot overwrite a read-only property.

// Flags: --es52_globals

function foobl() {}
assertTrue(typeof this.foobl == "function");
assertTrue(Object.getOwnPropertyDescriptor(this, "foobl").writable);

Object.defineProperty(this, "foobl", {value: 1, writable: false});
assertSame(1, this.foobl);
assertFalse(Object.getOwnPropertyDescriptor(this, "foobl").writable);

// This has to run in global scope, so cannot use assertThrows...
try {
  eval("function foobl() {}");  // Should throw.
  assertUnreachable();
} catch (e) {
  assertInstanceof(e, TypeError);
}
assertSame(1, this.foobl);