This came up in a game last month and i was looking at the wording of Test run.

Test Run

Search your stack or heap for a program. Install that program, ignoring all costs. Shuffle your stack if you searched it. When this turn ends, add the program to the top of your stack if it is still installed.

Scavenge

As an additional cost to play this card, trash an installed program.
Install a program from your grip or heap, lowering the install cost of that program by the cost of the program trashed.

They played Test Run then used Scavenge to trash Garrote and to re-install it, Witch is fine.

But what i thought was because of the wording on Test run. Because it is still installed dont you have to put the program back on top of ur deck as it is still installed at the end of your turn.

its was played as being left in but wanted input on this from anyone that has come acros this before and played it diffrently.

This is answered officially in the FAQ (I think) but anyway: cards in Netrunner have no memory. When you trash a program and re-install it, it doesn't 'remember' that you used Test Run to install it first; it counts as a whole new installation. Therefore you do not return it to the Stack at turn end, making it a great combo to install expensive programs such as Garrotte or Femme Fatale cheaply.

CommissarFeesh is correct. It is not still installed, it is installed again.