From 85d0348844df8c62ce9e15f022df505b9d3a4aee Mon Sep 17 00:00:00 2001
From: kai-morich <mail@kai-morich.de>
Date: Sun, 31 Jan 2021 19:56:43 +0100
Subject: [PATCH] improve error quality + test for PR #339

---
 .../java/com/hoho/android/usbserial/DeviceTest.java            | 2 +-
 .../com/hoho/android/usbserial/driver/CommonUsbSerialPort.java | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/DeviceTest.java b/usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/DeviceTest.java
index 345ccfc..70403e6 100644
--- a/usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/DeviceTest.java
+++ b/usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/DeviceTest.java
@@ -1846,7 +1846,7 @@ public class DeviceTest {
         try {
             usb.open(EnumSet.of(UsbWrapper.OpenCloseFlags.NO_IOMANAGER_THREAD, UsbWrapper.OpenCloseFlags.NO_DEVICE_CONNECTION));
             fail("open error expected");
-        } catch (IOException ignored) {
+        } catch (Exception ignored) {
         }
 
         usb.open(EnumSet.of(UsbWrapper.OpenCloseFlags.NO_IOMANAGER_THREAD));
diff --git a/usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/CommonUsbSerialPort.java b/usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/CommonUsbSerialPort.java
index 357865f..0ff1623 100644
--- a/usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/CommonUsbSerialPort.java
+++ b/usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/CommonUsbSerialPort.java
@@ -93,6 +93,9 @@ public abstract class CommonUsbSerialPort implements UsbSerialPort {
         if (mConnection != null) {
             throw new IOException("Already open");
         }
+        if(connection == null) {
+            throw new IllegalArgumentException("Connection is null");
+        }
         mConnection = connection;
         try {
             openInt(connection);