routing+channeldb: add AddProof method

Originally we adding the edge without proof in order to able to use it
for payments path constrcution. This method will allow us to populate
the announcement proof after the exchange of the half proofs and
constrcutrion of full proof finished.

routing/router_test.go

@@ -206,3 +206,51 @@ func TestSendPaymentRouteFailureFallback(t *testing.T) {
 			route.Hops[0].Channel.Node.Alias)
 	}
 }
+
+// TestAddProof checks that we can update the channel proof after channel
+// info was added to the database.
+func TestAddProof(t *testing.T) {
+	ctx, cleanup, err := createTestCtx(0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer cleanup()
+
+	// In order to be able to add the edge we should have the valud
+	// funding UTXO within the blockchain.
+	fundingTx, _, chanID, err := createChannelEdge(ctx,
+		bitcoinKey1.SerializeCompressed(), bitcoinKey2.SerializeCompressed(),
+		100, 0)
+	if err != nil {
+		t.Fatalf("unable create channel edge: %v", err)
+	}
+
+	fundingBlock := &wire.MsgBlock{
+		Transactions: []*wire.MsgTx{fundingTx},
+	}
+	ctx.chain.addBlock(fundingBlock, chanID.BlockHeight)
+
+	// After utxo was recreated adding the edge without the proof.
+	edge := &channeldb.ChannelEdgeInfo{
+		ChannelID:   chanID.ToUint64(),
+		NodeKey1:    priv1.PubKey(),
+		NodeKey2:    priv1.PubKey(),
+		BitcoinKey1: bitcoinKey1,
+		BitcoinKey2: bitcoinKey2,
+		AuthProof:   nil,
+	}
+
+	if err := ctx.router.AddEdge(edge); err != nil {
+		t.Fatalf("unable to add edge: %v", err)
+	}
+
+	// No trying to update the proof and checking that it have been updated.
+	if err := ctx.router.AddProof(*chanID, &testAuthProof); err != nil {
+		t.Fatalf("unable to add proof: %v", err)
+	}
+
+	info, _, _, err := ctx.router.GetChannelByID(*chanID)
+	if info.AuthProof == nil {
+		t.Fatal("proof have been updated")
+	}
+}