If you are interested in seeing a template for a test procedure to use a guide or format for other test procedures, I suggest you look at MIL-STD-810H "Environmental Engineering Considerations and Laboratory Tests."  You can find a free copy here:

https://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=35978  

Go through the table of contents and see if anything there looks about right for what you need.  Or, I suggest you might want to begin with Part Two "Laboratory Test Methods."  Here you will find a couple dozen specific types of environmental tests with very clear guidance and templates.  I am pretty sure any one of these could be a good template to follow. 

If you still don't find a good template to adopt/follow within MIL-STD-810H, the I suggest you explore the ASSIST database.  Go to the ASSIST database:  https://quicksearch.dla.mil/qsSearch.aspx and just start searching.  To streamline your search Just type “MIL” in the Document ID, select “Active” if all you want are current/valid documents and then go to the Find term box and type in any free text of what you are looking for.  A quick search for active MIL type documents containing the term "reliability" found 8 full pages.  Some are military specifications, some are military standards and there are other documents as well.  After a while you will figure out what you are looking for and my guess is you will pretty quickly find just what you are looking for.