Word order "I always should test..." vs "I should always test..."

As a non-native English speaker I am not sure about the word order in sentences with adverbs when used in the "in-between scenario" (according to https://english.stackexchange.com/a/9602/9579). In this specific case, is it correct to say

I always should test...

or

I should always test...

The adverb is in both cases between subject and verb, but the tricky bit here is that the verb has two components ("should" and "test"), making two in-between scenarios possible...

The order you mention second ("I should always test") is the usual order in English. However, sometimes, you might want to put emphasis on the auxiliary or modal verb ("should", in your examples), and in those situations your first order ("I always should test") is OK.