Add unit test for LibUsbException class.

src/test/java/org/usb4java/LibUsbExceptionTest.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2014 Klaus Reimer <k@ailis.de>
+ * See LICENSE.md for licensing information.
+ */
+
+package org.usb4java;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+/**
+ * Tests the {@link LibUsbException} class.
+ * 
+ * @author Klaus Reimer (k@ailis.de)
+ */
+public class LibUsbExceptionTest
+{
+    /**
+     * Tests the constructor with only an error code.
+     */
+    @Test
+    public void testConstructorWithCode()
+    {
+        final LibUsbException e =
+            new LibUsbException(LibUsb.ERROR_INVALID_PARAM);
+        assertEquals(LibUsb.ERROR_INVALID_PARAM, e.getErrorCode());
+        assertEquals("USB error 2: Invalid parameter", e.getMessage());
+
+    }
+
+    /**
+     * Tests the constructor with an error code and a message.
+     */
+    @Test
+    public void testConstructorWithCodeAndMessage()
+    {
+        final LibUsbException e =
+            new LibUsbException("Custom message", LibUsb.ERROR_INVALID_PARAM);
+        assertEquals(LibUsb.ERROR_INVALID_PARAM, e.getErrorCode());
+        assertEquals("USB error 2: Custom message: Invalid parameter", 
+            e.getMessage());
+
+    }
+}