/execute @a ~ ~ ~ detect ~ ~ ~ minecraft:portal 0 say test not working

Portals have different Damage values depending on the direction they are facing. According to your picture, the command block is running and you are not standing within a portal, so it's going to fail no matter what.

If you want to detect a player in a portal regardless of Damage value, you can set the Damage to -1:

/execute @a ~ ~ ~ detect ~ ~ ~ minecraft:portal -1 say test

@Skylinerw That was the case even when i even used /setblock ~ ~ ~ portal to place the portal Thanks

@unknown for the future please do not remove the complete title, just add for example "[SOLVED]" behind it. However this is not really needed as you are able to search by Resolution.
It could be helpful for other people to find this report and see what they did wrong before creating a new report 🙂