Array.prototype.indexOf does not work with interop collections

[ivan-menshikov]

If I try to use Array.prototype.indexOf with interop collection such as List<T> it returns -1 for any argument until I call something like Object.keys to create properties (actually I'm using SetPrototypeOf with my custom collection, but I think it's not important).

It seems the issue occurs because ObjectInstanceOperations.GetSmallestIndex returns the length of the collection if there are no cached properties for indices.

[Fact]
public void ArrayPrototypeIndexOfWithInteropList()
{
    var engine = new Jint.Engine();

    engine.SetValue("list", new List<string> { "A", "B", "C" });

    // ok: interop methods IndexOf and LastIndexOf of List<T> are used
    Assert.Equal(1, engine.Evaluate("list.indexOf('B')"));
    Assert.Equal(1, engine.Evaluate("list.lastIndexOf('B')"));

    // error: returns -1 because list does not have properties 0, 1 or 2
    Assert.Equal(-1, engine.Evaluate("Array.prototype.indexOf.call(list, 'B')"));
    // ok: this method does not use GetSmallestIndex
    Assert.Equal(1, engine.Evaluate("Array.prototype.lastIndexOf.call(list, 'B')"));

    // call any method that creates properties
    engine.Execute("Object.keys(list);");

    // now this works as expected
    Assert.Equal(1, engine.Evaluate("Array.prototype.indexOf.call(list, 'B')"));
}

[lahma]

Thanks for the report, fix should be soon available on MyGet feed, later at some point on the NuGet feed.