lntest+itest: add new method AssertChannelInGraph

This commit replaces `AssertTopologyChannelOpen` with
`AssertChannelInGraph`, which asserts a given channel edge is found.
`AssertTopologyChannelOpen` only asserts a given edge has been received
via the topology subscription, while we need to make sure the channel is
in the graph before continuing our tests.

lntest/harness_assertion.go

@@ -403,15 +403,6 @@ func (h HarnessTest) WaitForChannelOpenEvent(
 	return resp.ChanOpen.ChannelPoint
 }
 
-// AssertTopologyChannelOpen asserts that a given channel outpoint is seen by
-// the passed node's network topology.
-func (h *HarnessTest) AssertTopologyChannelOpen(hn *node.HarnessNode,
-	chanPoint *lnrpc.ChannelPoint) {
-
-	err := hn.Watcher.WaitForChannelOpen(chanPoint)
-	require.NoErrorf(h, err, "%s didn't report channel", hn.Name())
-}
-
 // AssertChannelExists asserts that an active channel identified by the
 // specified channel point exists from the point-of-view of the node.
 func (h *HarnessTest) AssertChannelExists(hn *node.HarnessNode,
@@ -506,7 +497,8 @@ func (h *HarnessTest) findChannel(hn *node.HarnessNode,
 		}
 	}
 
-	return nil, fmt.Errorf("channel not found using %s", chanPoint)
+	return nil, fmt.Errorf("%s: channel not found using %s", hn.Name(),
+		fp.String())
 }
 
 // ReceiveCloseChannelUpdate waits until a message or an error is received on
@@ -1945,6 +1937,37 @@ func (h *HarnessTest) AssertNotInGraph(hn *node.HarnessNode, chanID uint64) {
 		"found in graph")
 }
 
+// AssertChannelInGraph asserts that a given channel is found in the graph.
+func (h *HarnessTest) AssertChannelInGraph(hn *node.HarnessNode,
+	chanPoint *lnrpc.ChannelPoint) *lnrpc.ChannelEdge {
+
+	ctxt, cancel := context.WithCancel(h.runCtx)
+	defer cancel()
+
+	var edge *lnrpc.ChannelEdge
+
+	op := h.OutPointFromChannelPoint(chanPoint)
+	err := wait.NoError(func() error {
+		resp, err := hn.RPC.LN.GetChanInfo(
+			ctxt, &lnrpc.ChanInfoRequest{
+				ChanPoint: op.String(),
+			},
+		)
+		if err != nil {
+			return fmt.Errorf("channel %s not found in graph: %w",
+				op, err)
+		}
+
+		edge = resp
+
+		return nil
+	}, DefaultTimeout)
+	require.NoError(h, err, "%s: timeout finding channel in graph",
+		hn.Name())
+
+	return edge
+}
+
 // AssertTxAtHeight gets all of the transactions that a node's wallet has a
 // record of at the target height, and finds and returns the tx with the target
 // txid, failing if it is not found.