How to check if provider is exist or not before the creating a new one ? because i'm getting error: Duplicate resource URN 'urnpulumidev:testproject hellow bcdpulumiprovidersgcp:gcp-provider-default'; try giving it a unique name

Each default provider should only be created once by Pulumi, as a user you can add multiple additional GCP providers in your program if you like. How are you ending up in this situation?

If you're constructing a provider, don't use the same name as the default provider. It looks like this one is called

gcp-provider-default

, so you should pick a different name.