The Halo Infinite cooperative will undergo public testing in July

It is expected that Hello Infiite will receive a major update for the joint game in August, which will allow you to roam the world with other players. If you participate in the program Hello Insider, or join it soon - you will be able to play in cooperative mode a month earlier, because 343 Industries announced public testing in July. 

Learn and join the program Hello Insider You can here, but keep in mind that participating in this program does not guarantee that you will be participating in a cooperative test. In any case, it's free, so you don't lose anything. 

The road map of the game, which was published in April, indicated at the end of August that the launch of the cooperative game is likely to be the case, as 343 Industries have not broken the schedule yet. A cooperative will be available online at the start, and a split-screen cooperative will be delivered later. Another expected addition is the mode Halo's Forge, which has yet to reach open beta in September. 

Source: PC Gamer