Function new_mock_session_with_capacity 

pub fn new_mock_session_with_capacity(
    peer_id: FixedBytes<64>,
    version: EthVersion,
    capacity: usize,
) -> (PeerMetadata, Receiver<PeerRequest>)

Available on crate features test-utils only.

Mock a new session whose request channel buffers up to capacity requests, returns (peer, channel-to-send-get-pooled-tx-response-on).