Mirror Approach is used before going to deliver the customer testing in the lab with the same configuration or environment of client using is called Mirror Approach.

Some language scripts such as Arabic and Hebrew are traditionally written
and read from right to left instead of from left to right. Users of
right-to-left language scripts not only expect text in their software
applications to flow from right to left they also expect that all of the
controls on a form flow from right to left. When you place text and controls on
a form in right-to-left order it is called mirroring because you are creating a
mirror image of the more common left-to-right order.

If you want to distribute your software to the markets where the text and
user interface of the programs display from right-to-left you will want to know
how your application looks when it is mirrored. This type of testing is called
mirror testing.