Inline/same file object type definition

I can define object type like so:

// Test.qml
import QtQuick 2.6

Rectangle {
    width: 50
    height: 50
}

and easily reuse with set properties like color

// main.qml
import QtQuick 2.6
import QtQuick.Window 2.2

Window {
    visible: true
    width: 640
    height: 480

    Test {
        color: "blue"
    }

    Test {
        x:50
        color: "red"
    }
}

But sometimes I have object that I would like to reuse only in a single file. So creating additional file for object that I would only reuse in that single file doesn't seem right.

Can Something similar shown in the example above be done in the same file?

Can Something similar shown in the example above be done in the same file?

This question seems similar to this one. You can use Loader or dynamic object creation, but I don't think that's better than moving the code to a separate file, as you've done in your example.

So creating additional file for object that I would only reuse in that single file doesn't seem right.

I disagree with this. It's still a benefit to reuse a component even if the reuse occurs in a single file. It's much clearer to read code that directly instantiates component instances rather than using loaders or dynamic object creation.