lntest: create GenBaseDir to generate the base dir

lntest/node/config.go

@@ -223,6 +223,23 @@ func (cfg *BaseNodeConfig) BaseConfig() *BaseNodeConfig {
 	return cfg
 }
 
+// GenBaseDir creates a base dir that's used for the test.
+func (cfg *BaseNodeConfig) GenBaseDir() error {
+	if cfg.BaseDir == "" {
+		var err error
+
+		// Create a temporary directory for the node's data and logs.
+		// Use dash suffix as a separator between base name and random
+		// suffix.
+		dirBaseName := fmt.Sprintf("lndtest-node-%s-", cfg.Name)
+		cfg.BaseDir, err = os.MkdirTemp("", dirBaseName)
+
+		return err
+	}
+
+	return nil
+}
+
 // GenArgs generates a slice of command line arguments from the lightning node
 // config struct.
 func (cfg *BaseNodeConfig) GenArgs() []string {

lntest/node/harness_node.go

@@ -93,18 +93,10 @@ type HarnessNode struct {
 // NewHarnessNode creates a new test lightning node instance from the passed
 // config.
 func NewHarnessNode(t *testing.T, cfg *BaseNodeConfig) (*HarnessNode, error) {
-	if cfg.BaseDir == "" {
-		var err error
-
-		// Create a temporary directory for the node's data and logs.
-		// Use dash suffix as a separator between base name and random
-		// suffix.
-		dirBaseName := fmt.Sprintf("lndtest-node-%s-", cfg.Name)
-		cfg.BaseDir, err = os.MkdirTemp("", dirBaseName)
-		if err != nil {
-			return nil, err
-		}
+	if err := cfg.GenBaseDir(); err != nil {
+		return nil, err
 	}
+
 	cfg.DataDir = filepath.Join(cfg.BaseDir, "data")
 	cfg.LogDir = filepath.Join(cfg.BaseDir, "logs")
 	cfg.TLSCertPath = filepath.Join(cfg.BaseDir, "tls.cert")