Coinbase Pro allows to use a SandBox account where you can trade without real funds. This account requires to create API keys different from production account.
To use the SandBox account, just set Coinbase.SandBox property to true, before do any request to API.
oCoinbase := TsgcWSAPI_Coinbase.Create(nil);
oCoinbase.Coinbase.ApiKey := 'your api key';
oCoinbase.Coinbase.ApiSecret := 'your api secret';
oCoinbase.Coinbase.ApiPassphrase := 'your passphrase';
oCoinbase.Coinbase.SandBox := True;
ShowMessage(oCoinbase.REST_API.ListAccounts);