lntest: specify lnd binary

Integration tests in external projects might not have the same folder
structure as lnd does. Therefore we want to allow the path to the
lnd itest binary to be configurable.

lntest/harness.go

@@ -35,6 +35,10 @@ const DefaultCSV = 4
 type NetworkHarness struct {
 	netParams *chaincfg.Params
 
+	// lndBinary is the full path to the lnd binary that was specifically
+	// compiled with all required itest flags.
+	lndBinary string
+
 	// Miner is a reference to a running full node that can be used to create
 	// new blocks on the network.
 	Miner *rpctest.Harness
@@ -68,7 +72,9 @@ type NetworkHarness struct {
 // TODO(roasbeef): add option to use golang's build library to a binary of the
 // current repo. This will save developers from having to manually `go install`
 // within the repo each time before changes
-func NewNetworkHarness(r *rpctest.Harness, b BackendConfig) (*NetworkHarness, error) {
+func NewNetworkHarness(r *rpctest.Harness, b BackendConfig, lndBinary string) (
+	*NetworkHarness, error) {
+
 	n := NetworkHarness{
 		activeNodes:          make(map[int]*HarnessNode),
 		nodesByPub:           make(map[string]*HarnessNode),
@@ -79,6 +85,7 @@ func NewNetworkHarness(r *rpctest.Harness, b BackendConfig) (*NetworkHarness, er
 		Miner:                r,
 		BackendCfg:           b,
 		quit:                 make(chan struct{}),
+		lndBinary:            lndBinary,
 	}
 	go n.networkWatcher()
 	return &n, nil
@@ -361,7 +368,7 @@ func (n *NetworkHarness) newNode(name string, extraArgs []string,
 	n.activeNodes[node.NodeID] = node
 	n.mtx.Unlock()
 
-	if err := node.start(n.lndErrorChan); err != nil {
+	if err := node.start(n.lndBinary, n.lndErrorChan); err != nil {
 		return nil, err
 	}
 
@@ -612,7 +619,7 @@ func (n *NetworkHarness) RestartNode(node *HarnessNode, callback func() error,
 		}
 	}
 
-	if err := node.start(n.lndErrorChan); err != nil {
+	if err := node.start(n.lndBinary, n.lndErrorChan); err != nil {
 		return err
 	}
 
@@ -643,7 +650,7 @@ func (n *NetworkHarness) SuspendNode(node *HarnessNode) (func() error, error) {
 	}
 
 	restart := func() error {
-		return node.start(n.lndErrorChan)
+		return node.start(n.lndBinary, n.lndErrorChan)
 	}
 
 	return restart, nil