Just reading the article on NZ Herald. it states:

The man police shot dead in an Auckland supermarket today after stabbing several shoppers is a known Isis sympathiser whom the police had previously arrested for allegedly planning a "lone wolf" knife attack.

later in the article:

Last year, the Crown had sought to prosecute S under the Terrorism Suppression Act 2002, but a High Court judge ruled that preparing a terrorist attack was not in itself an offence under the legislation.

Section 25 of the Terrorist Suppression Act 2002: https://i.imgur.com/8dWPR3g.png

I don't understand how that doesn't quite clearly state that preparing a terrorist attack is counted as a terrorist act.