Test Run reads:
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.
When Harbinger is trashed, install it facedown instead of adding it to your heap.
Suppose I use Test Run to bring a Harbinger out of my Heap, then trash Harbinger so that it becomes installed face down. Does Test Run put it on my deck at the end of my turn, or does it stay installed face down?