We recently discussed that article in a German forum, and came to the conclusion that the term
test coins is somewhat misleading. The Finnish Mint (which makes the Slovenian euro coins) will not really need any testing.

It is more likely that the Slovenian government wants a certain amount of coins to be ready (for frontloading and sub-frontloading) by the time the country switches, probably on 1 January. That would be those 8 x 2 million coins with a "Slovenian" obverse.
By the way, as from tomorrow most prices in Slovenia will have to be displayed in both tolar and euro.
http://www.gzs.si/eng/news/sbw/head.asp?idc=20724Christian