I'm in charge of editing our auto-respond journeys. It's a HUGE pain to set up a fake trigger and test segment just to test what all the emails will look like to the end user.
SUGGEST:
1) Add "Send a this email once to: " [ _____________]" in the Send Email block in the journey. User fills in their email address and hits [SEND]. This email isn't added to the journey nor counted. It's just for testing.
ALTERNATIVE IDEA:
1) In the Journey editing UI, add "Test Journey with this email: [________] (TEST BUTTON)" which sends all the emails in the journey to the entered user in order.
This solves the problem of having to so the suggestion above 25 times in a row! It also solves the problem of testing the journey which has delays in it (ours have 25 1 day delays which I have to change to 5min for testing purposes)