delpay: code style changes and fixed docs

Changelog-Added: JSON-RPC: delpay a new method to delete the payment completed or failed.

Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>

tests/test_pay.py

@@ -3263,6 +3263,107 @@ def test_mpp_presplit_routehint_conflict(node_factory, bitcoind):
     l1.rpc.pay(inv)
 
 
+def test_delpay_argument_invalid(node_factory, bitcoind):
+    """
+    This test includes all possible combination of input error inside the
+    delpay command.
+    """
+
+    l1, l2 = node_factory.get_nodes(2)
+
+    with pytest.raises(RpcError):
+        l2.rpc.delpay()
+
+    # invoice unpayed
+    inv = l1.rpc.invoice(10 ** 5, 'inv', 'inv')
+    payment_hash = inv["payment_hash"]
+    with pytest.raises(RpcError):
+        l2.rpc.delpay(payment_hash)
+
+    # payment unpayed with wrong status (pending status is a illegal input)
+    with pytest.raises(RpcError):
+        l2.rpc.delpay(payment_hash, 'pending')
+
+    with pytest.raises(RpcError):
+        l2.rpc.delpay(payment_hash, 'invalid_status')
+
+    l2.rpc.connect(l1.info['id'], 'localhost', l1.port)
+    l2.fund_channel(l1, 10 ** 6)
+
+    bitcoind.generate_block(6)
+    sync_blockheight(bitcoind, [l1, l2])
+
+    wait_for(lambda: len(l2.rpc.listchannels()['channels']) == 2)
+
+    l2.rpc.pay(inv['bolt11'])
+
+    with pytest.raises(RpcError):
+        l2.rpc.delpay(payment_hash, 'failed')
+
+    with pytest.raises(RpcError):
+        l2.rpc.delpay(payment_hash, 'pending')
+
+    assert len(l2.rpc.listpays()['pays']) == 1
+
+    # test if the node is still ready
+    payments = l2.rpc.delpay(payment_hash, 'complete')
+
+    assert payments['payments'][0]['bolt11'] == inv['bolt11']
+    assert len(payments['payments']) == 1
+    assert len(l2.rpc.listpays()['pays']) == 0
+
+
+def test_delpay(node_factory, bitcoind):
+    """
+    This unit test try to catch some error inside the command
+    delpay when it receives the correct input from the user
+    """
+
+    l1, l2 = node_factory.get_nodes(2)
+
+    amount_sat = 10 ** 6
+
+    # create l2->l1 channel.
+    l2.fundwallet(amount_sat * 5)
+    l1.rpc.connect(l2.info['id'], 'localhost', l2.port)
+    l2.rpc.fundchannel(l1.info['id'], amount_sat * 3)
+
+    # Let the channel confirm.
+    bitcoind.generate_block(6)
+    sync_blockheight(bitcoind, [l1, l2])
+
+    invl1 = l1.rpc.invoice(Millisatoshi(amount_sat * 2 * 1000), "j", "j")
+    l2.rpc.pay(invl1["bolt11"])
+
+    before_del_pay = l2.rpc.listpays()
+
+    l2.rpc.delpay(invl1["payment_hash"])
+
+    after_del_pay = l2.rpc.listpays()["pays"]
+    assert len(after_del_pay) == (len(before_del_pay) - 1)
+
+
+def test_delpay_payment_split(node_factory, bitcoind):
+    """
+    This test test the correct bheaivord of the commmand delpay with a mpp
+    """
+    MPP_TARGET_SIZE = 10**7  # Taken from libpluin-pay.c
+    amt = 5 * MPP_TARGET_SIZE
+
+    l1, l2, l3 = node_factory.line_graph(
+        3, fundamount=10**8, wait_for_announce=True,
+        opts={'wumbo': None}
+    )
+
+    inv = l3.rpc.invoice(amt, 'lbl', 'desc')
+    l1.rpc.pay(inv['bolt11'])
+
+    assert len(l1.rpc.listpays()['pays']) == 1
+    delpay_result = l1.rpc.delpay(inv['payment_hash'], 'complete')['payments']
+    assert len(delpay_result) >= 5
+    assert len(l1.rpc.listpays()['pays']) == 0
+
+
 def test_listpay_result_with_paymod(node_factory, bitcoind):
     """
     The object of this test is to verify the correct behavior