I'm conflating the final two beatitudes. One promises the Kingdom of God if you're persecuted for the sake of justice/righteousness. The other promises a great reward in heaven for those hated on and persecuted "on my account". This final beatitude ends, unusually, with Jesus offering a historical consolation: "for in the same way they persecuted the prophets who were before you".
For Jesus, the prophets were outsiders, murdered by the same type of people who were planning to murder him (Matt 23.29-36). Now, in the Kingdom he was inaugurating, the "prophets, sages, and scribes" Jesus is sending, can also expect the prophet's fate (Matt 23.34). Persecution, it seems, is part of the mix when you follow Jesus and pursue his life of justice.
It seems to me that the beatitudes envisage communities that confront a 'business as usual' type of life. They are salt and light, which makes them prophetic, and liable to misunderstanding and persecution. The real question isn't whether followers of Jesus will get persecuted, but why? Is it "for the sake of justice and Jesus', or is it because Christians are anxious to hold onto what status and standing they have accrued. Watching America from the very post-Christendom outpost of Aotearoa, the Christian complaints about losing 'religious freedom' sound more like the second.
I don't think it's our job to be persecuted. It's our job to stand out for Jesus. That will bring persecution enough. Then comes the challenge of loving our enemies and forsaking violence as a response. Whenever I hear Christians doing that I'm humbled, grateful and proud to be on their team.
So what can I do to test this beatitude? Stand out for Jesus and discipline myself to love my enemies and not respond with violence.