Set baudrate, add mock serial struct to test with.

Sources/SwiftRPLidar/LidarSerial.swift

@@ -7,4 +7,5 @@ public protocol LidarSerial {
     func openPort() throws;
     func readData(ofLength: Int) throws -> Data;
     func writeData(_ data: Data) throws -> Int;
+    func setBaudrate(baudrate: Int)
 }

Sources/SwiftRPLidar/SwiftRPLidar.swift

@@ -78,6 +78,7 @@ public class SwiftRPLidar {
     public func connect() throws {
         disconnect()
         try serialPort!.openPort()
+        serialPort?.setBaudrate(baudrate: 115200)
     }
     
     public func disconnect(){

Tests/SwiftRPLidarTests/SwiftRPLidarTests.swift

@@ -13,3 +13,28 @@ final class SwiftRPLidarTests: XCTestCase {
         ("testExample", testExample),
     ]
 }
+
+struct MockSerialPort: LidarSerial {
+    
+    var dtr: Bool
+    
+    var inWaiting: Int
+    
+    func closePort() {
+    }
+    
+    func openPort() throws {
+    }
+    
+    func readData(ofLength: Int) throws -> Data {
+        return Data()
+    }
+    
+    func writeData(_ data: Data) throws -> Int {
+        return 0
+    }
+    
+    func setBaudrate(baudrate: Int) {
+        
+    }
+}