Generate a P2SH-P2WSH address, create a tx spending from it.

p2sh_p2wsh.rb

require 'btcruby'
require 'bitcoin'
require 'active_support'
require 'active_support/core_ext'
require 'ffi'

# Creation of Witness Script: here a 2-of-2 multisig as an example

@public_key = "02530c548d402670b13ad8887ff99c294e67fc18097d236d57880c69261b42def7"
@user_key = BTC::Key.new(public_key:BTC.from_hex(@public_key))
@escrow_key = BTC::Key.new(public_key:BTC.from_hex("024fffe85607b555cf7697e4be0d3d34dc1868baa57c235d926e447e926c08d287"))

witness_script = BTC::Script.new  << BTC::Script::OP_2 << @user_key.compressed_public_key << @escrow_key.compressed_public_key << BTC::Script::OP_2 
witness_script << BTC::Script::OP_CHECKMULTISIG
@witness_script = witness_script.data

redeem_script = BTC::Script.new   
redeem_script<< BTC::Script::OP_0
redeem_script<< BTC.sha256(@witness_script)

# Computation of P2SH-P2WPKH address
p2sh_p2wsh_address = BTC::ScriptHashAddress.new(redeem_script:redeem_script).to_s # exemple: 34c48TmtAUSpPZS5X1X8USNAUSWvZau6zn

# Transaction spending from P2SH-P2WPKH address

include Bitcoin::Builder
include Bitcoin::Protocol
include Bitcoin::Secp256k1
@destination_address = "1Bwyn5f5EvUPazh3H2rns6ENjTUYnK9ben"
user_key = Bitcoin.open_key("25940ed...f7b2d9") # <- privkey in hex
escrow_key = Bitcoin.open_key("4b5b5e...975c")

prev_out="4922998c3a2f741a64c85f2bce7367485ff25495dfd349e3ae60e5265ed6381d"
prev_out_index = 0
value = 100000
fee = 15000

witness_script = Bitcoin::Script.new(@witness_script)
@redeem_script = redeem_script.data

spend_tx = build_tx do |t|
  t.lock_time 0
  t.input do |i|
    i.prev_out prev_out, prev_out_index, @redeem_script, value
    i.sequence "ffffffff".htb
  end
  t.output do |o|
    o.value value-fee
    o.script {|s| s.recipient @destination_address }
  end
end

tx = Tx.new(spend_tx.to_payload) # yet unsigned tx

tx.in[0].script_sig = Bitcoin::Script.new(Bitcoin::Script.pack_pushdata(@redeem_script)).to_payload

tx.in[0].script_witness.stack << ''

sig_hash = tx.signature_hash_for_witness_input(0, @redeem_script, value, witness_script.to_payload, Tx::SIGHASH_TYPE[:all])
sig0 = Bitcoin::Secp256k1.sign(sig_hash, user_key.private_key.to_hex.htb) + [Tx::SIGHASH_TYPE[:all]].pack("C")
tx.in[0].script_witness.stack << sig0

sig1 = Bitcoin::Secp256k1.sign(sig_hash, escrow_key.private_key.to_hex.htb) + [Tx::SIGHASH_TYPE[:all]].pack("C")
tx.in[0].script_witness.stack << sig1
tx.in[0].script_witness.stack << witness_script.to_payload
tx.to_witness_payload.bth
# tx id: 718b84ed26a1178efc61b6b500d775df6392fb91816c2e7a48b9d018d66159c4