Regarding a simple test for upper body strength, nothing beats bench press hence it is still widely used in coaching and strength testing. For trunk strength, the overhead medicine ball throw works well as it recruits multiple muscle groups and can be used for testing both power and endurance.
I agree with others that the key muscle groups for goalies to focus on during off-ice training are quads and hips, as well as trunk. Nevertheless, goalies should not completely ignore other muscle groups as goaltending is a somewhat thorough fitness experience.
A bit off from the original discussion whether goalies need upper body strength, there is also a study available where the authors aimed to identify off-ice variables that would correlate to on-ice skating sprint performance and cornering ability, and found that measures of horizontal leg power (here, off-ice sprint and 3 hop jump) were the best predictors of on-ice skating performance.
http://www.ncbi.nlm.nih.gov/sites/entre ... m=17685681
Yet in other study were the physiological profile of a NHL team over a period of 26 years was examined, the overall pre-season fitness profile was not, at least directly, found to be related to team success.
http://article.pubs.nrc-cnrc.gc.ca/ppv/ ... rtPage=753
On the other hand, in another study the higher physical fitness of a player predicted his/her net scoring chances, supporting the value of implementing seasonal physiological testing, which will help strength and conditioning coaches make individualized modifications to a player's fitness regimens in an effort to improve specific physiological attributes.
http://www.ncbi.nlm.nih.gov/sites/entre ... m=16562362
Out of the ordinary... out of this world.