SegWit witness commitment merkle root location BIP 141 defines the commitment structure here
What i am unsure about is the location of this data. I know it will be in scriptPubKey.
Does this mean Coinbase tx will have more than one output?
Also is there a testnet block with an example of a Coinbase tx with witness commitment?
The witness commitment is in an OP_RETURN output of the coinbase transaction. This means that the coinbase transaction will likely have more than 1 output (although not necessarily as a miner could send the block reward to the OP_RETURN output, but they would be stupid to do so). Here is a testnet block with a witness commitment: https://live.blockcypher.com/btc-testnet/block/00000000000007972a6f786179cb42dbc59f167aafd757b203e6c2eb80d49455/. All testnet blocks should have one as segwit has activated on testnet.