test: receivable_msat similar to spendable_msat

tests/test_pay.py

@@ -2245,6 +2245,59 @@ def test_channel_spendable(node_factory, bitcoind):
     l2.rpc.waitsendpay(payment_hash, TIMEOUT)
 
 
+@unittest.skipIf(not DEVELOPER, "gossip without DEVELOPER=1 is slow")
+def test_channel_receivable(node_factory, bitcoind):
+    """Test that receivable_msat is accurate"""
+    sats = 10**6
+    l1, l2 = node_factory.line_graph(2, fundamount=sats, wait_for_announce=True,
+                                     opts={'plugin': os.path.join(os.getcwd(), 'tests/plugins/hold_invoice.py'), 'holdtime': str(TIMEOUT / 2)})
+
+    payment_hash = l2.rpc.invoice('any', 'inv', 'for testing')['payment_hash']
+
+    # We should be able to receive this much, and not one msat more!
+    amount = l2.rpc.listpeers()['peers'][0]['channels'][0]['receivable_msat']
+    route = l1.rpc.getroute(l2.info['id'], amount + 1, riskfactor=1, fuzzpercent=0)['route']
+    l1.rpc.sendpay(route, payment_hash)
+
+    # This should fail locally with "capacity exceeded"
+    with pytest.raises(RpcError, match=r"Capacity exceeded.*'erring_index': 0"):
+        l1.rpc.waitsendpay(payment_hash, TIMEOUT)
+
+    # Exact amount should succeed.
+    route = l1.rpc.getroute(l2.info['id'], amount, riskfactor=1, fuzzpercent=0)['route']
+    l1.rpc.sendpay(route, payment_hash)
+
+    # Amount should drop to 0 once HTLC is sent; we have time, thanks to
+    # hold_invoice.py plugin.
+    wait_for(lambda: len(l2.rpc.listpeers()['peers'][0]['channels'][0]['htlcs']) == 1)
+    assert l2.rpc.listpeers()['peers'][0]['channels'][0]['receivable_msat'] == Millisatoshi(0)
+    l1.rpc.waitsendpay(payment_hash, TIMEOUT)
+
+    # Make sure l2 thinks it's all over.
+    wait_for(lambda: len(l2.rpc.listpeers()['peers'][0]['channels'][0]['htlcs']) == 0)
+    # Now, reverse should work similarly.
+    payment_hash = l1.rpc.invoice('any', 'inv', 'for testing')['payment_hash']
+    amount = l1.rpc.listpeers()['peers'][0]['channels'][0]['receivable_msat']
+
+    # Turns out we this won't route, as it's over max - reserve:
+    route = l2.rpc.getroute(l1.info['id'], amount + 1, riskfactor=1, fuzzpercent=0)['route']
+    l2.rpc.sendpay(route, payment_hash)
+
+    # This should fail locally with "capacity exceeded"
+    with pytest.raises(RpcError, match=r"Capacity exceeded.*'erring_index': 0"):
+        l2.rpc.waitsendpay(payment_hash, TIMEOUT)
+
+    # Exact amount should succeed.
+    route = l2.rpc.getroute(l1.info['id'], amount, riskfactor=1, fuzzpercent=0)['route']
+    l2.rpc.sendpay(route, payment_hash)
+
+    # Amount should drop to 0 once HTLC is sent; we have time, thanks to
+    # hold_invoice.py plugin.
+    wait_for(lambda: len(l1.rpc.listpeers()['peers'][0]['channels'][0]['htlcs']) == 1)
+    assert l1.rpc.listpeers()['peers'][0]['channels'][0]['receivable_msat'] == Millisatoshi(0)
+    l2.rpc.waitsendpay(payment_hash, TIMEOUT)
+
+
 @unittest.skipIf(not DEVELOPER, "gossip without DEVELOPER=1 is slow")
 def test_channel_spendable_large(node_factory, bitcoind):
     """Test that spendable_msat is accurate for large channels"""
@@ -2256,26 +2309,31 @@ def test_channel_spendable_large(node_factory, bitcoind):
     payment_hash = l2.rpc.invoice('any', 'inv', 'for testing')['payment_hash']
 
     # We should be able to spend this much, and not one msat more!
-    amount = l1.rpc.listpeers()['peers'][0]['channels'][0]['spendable_msat']
+    spendable = l1.rpc.listpeers()['peers'][0]['channels'][0]['spendable_msat']
+
+    # receivable from the other side should calculate to the exact same amount
+    receivable = l1.rpc.listpeers()['peers'][0]['channels'][0]['spendable_msat']
+    assert spendable == receivable
 
     # route or waitsendpay fill fail.
     with pytest.raises(RpcError):
-        route = l1.rpc.getroute(l2.info['id'], amount + 1, riskfactor=1, fuzzpercent=0)['route']
+        route = l1.rpc.getroute(l2.info['id'], receivable + 1, riskfactor=1, fuzzpercent=0)['route']
         l1.rpc.sendpay(route, payment_hash)
         l1.rpc.waitsendpay(payment_hash, TIMEOUT)
 
     print(l2.rpc.listchannels())
     # Exact amount should succeed.
-    route = l1.rpc.getroute(l2.info['id'], amount, riskfactor=1, fuzzpercent=0)['route']
+    route = l1.rpc.getroute(l2.info['id'], spendable, riskfactor=1, fuzzpercent=0)['route']
     l1.rpc.sendpay(route, payment_hash)
     l1.rpc.waitsendpay(payment_hash, TIMEOUT)
 
 
-def test_channel_spendable_capped(node_factory, bitcoind):
-    """Test that spendable_msat is capped at 2^32-1"""
+def test_channel_spendable_receivable_capped(node_factory, bitcoind):
+    """Test that spendable_msat and receivable_msat is capped at 2^32-1"""
     sats = 16777215
     l1, l2 = node_factory.line_graph(2, fundamount=sats, wait_for_announce=False)
     assert l1.rpc.listpeers()['peers'][0]['channels'][0]['spendable_msat'] == Millisatoshi(0xFFFFFFFF)
+    assert l2.rpc.listpeers()['peers'][0]['channels'][0]['receivable_msat'] == Millisatoshi(0xFFFFFFFF)
 
 
 def test_lockup_drain(node_factory, bitcoind):