improve the exceptions

also adds a stump for the tests for MagicEncode

src/escpos/exceptions.py

@@ -87,7 +87,7 @@ class BarcodeCodeError(Error):
         self.resultcode = 30
 
     def __str__(self):
-        return "No Barcode code was supplied"
+        return "No Barcode code was supplied ({msg})".format(msg=self.msg)
 
 
 class ImageSizeError(Error):
@@ -101,7 +101,7 @@ class ImageSizeError(Error):
         self.resultcode = 40
 
     def __str__(self):
-        return "Image height is longer than 255px and can't be printed"
+        return "Image height is longer than 255px and can't be printed ({msg})".format(msg=self.msg)
 
 
 class TextError(Error):
@@ -116,7 +116,7 @@ class TextError(Error):
         self.resultcode = 50
 
     def __str__(self):
-        return "Text string must be supplied to the text() method"
+        return "Text string must be supplied to the text() method ({msg})".format(msg=self.msg)
 
 
 class CashDrawerError(Error):
@@ -131,7 +131,7 @@ class CashDrawerError(Error):
         self.resultcode = 60
 
     def __str__(self):
-        return "Valid pin must be set to send pulse"
+        return "Valid pin must be set to send pulse ({msg})".format(msg=self.msg)
 
 
 class TabPosError(Error):
@@ -146,7 +146,7 @@ class TabPosError(Error):
         self.resultcode = 70
 
     def __str__(self):
-        return "Valid tab positions must be in the range 0 to 16"
+        return "Valid tab positions must be in the range 0 to 16 ({msg})".format(msg=self.msg)
 
 
 class CharCodeError(Error):
@@ -161,7 +161,7 @@ class CharCodeError(Error):
         self.resultcode = 80
 
     def __str__(self):
-        return "Valid char code must be set"
+        return "Valid char code must be set ({msg})".format(msg=self.msg)
 
 
 class USBNotFoundError(Error):
@@ -176,7 +176,7 @@ class USBNotFoundError(Error):
         self.resultcode = 90
 
     def __str__(self):
-        return "USB device not found"
+        return "USB device not found ({msg})".format(msg=self.msg)
 
 
 class SetVariableError(Error):
@@ -191,7 +191,7 @@ class SetVariableError(Error):
         self.resultcode = 100
 
     def __str__(self):
-        return "Set variable out of range"
+        return "Set variable out of range ({msg})".format(msg=self.msg)
 
 
 # Configuration errors

test/test_magicencode.py

@@ -0,0 +1,54 @@
+#!/usr/bin/python
+"""tests for panel button function
+
+:author: `Patrick Kanzler <patrick.kanzler@fablab.fau.de>`_
+:organization: `python-escpos <https://github.com/python-escpos>`_
+:copyright: Copyright (c) 2016 `python-escpos <https://github.com/python-escpos>`_
+:license: GNU GPL v3
+"""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+from __future__ import unicode_literals
+
+from nose.tools import with_setup
+
+import escpos.printer as printer
+import os
+
+devfile = 'testfile'
+
+
+def setup_testfile():
+    """create a testfile as devfile"""
+    fhandle = open(devfile, 'a')
+    try:
+        os.utime(devfile, None)
+    finally:
+        fhandle.close()
+
+
+def teardown_testfile():
+    """destroy testfile again"""
+    os.remove(devfile)
+
+
+@with_setup(setup_testfile, teardown_testfile)
+def test_function_panel_button_on():
+    """test the panel button function (enabling) by comparing output"""
+    instance = printer.File(devfile=devfile)
+    instance.panel_buttons()
+    instance.flush()
+    with open(devfile, "rb") as f:
+        assert(f.read() == b'\x1B\x63\x35\x00')
+
+
+@with_setup(setup_testfile, teardown_testfile)
+def test_function_panel_button_off():
+    """test the panel button function (disabling) by comparing output"""
+    instance = printer.File(devfile=devfile)
+    instance.panel_buttons(False)
+    instance.flush()
+    with open(devfile, "rb") as f:
+        assert(f.read() == b'\x1B\x63\x35\x01')