Add an exception for missing configuration sections

escpos/config.py

@@ -46,11 +46,15 @@ class Config(object):
             )
 
         try:
-            if isinstance(config_path, str):
+            # First check if it's file like. If it is, pyyaml can load it.
+            # I'm checking type instead of catching excpetions to keep the
+            # exception handling simple
+            if hasattr(config_path, 'read'):
+                config = yaml.safe_load(config_path)
+            else:
+                # If it isn't, it's a path. We have to open it first.
                 with open(config_path, 'rb') as config_file:
                     config = yaml.safe_load(config_file)
-            else:
-                config = yaml.safe_load(config_path)
         except EnvironmentError:
             raise exceptions.ConfigNotFoundError('Couldn\'t read config at {config_path}'.format(
                 config_path=str(config_path),
@@ -72,7 +76,8 @@ class Config(object):
         self._has_loaded = True
 
     def printer(self):
-        """ Returns a printer that was defined in the config, or None.
+        """ Returns a printer that was defined in the config, or throws an
+        exception.
 
         This method loads the default config if one hasn't beeen already loaded.
 
@@ -80,6 +85,9 @@ class Config(object):
         if not self._has_loaded:
             self.load()
 
+        if not self._printer_name:
+            raise exceptions.ConfigSectionMissingError('printer')
+
         if not self._printer:
             # We could catch init errors and make them a ConfigSyntaxError,
             # but I'll just let them pass

escpos/exceptions.py

@@ -15,6 +15,7 @@ Result/Exit codes:
     - `100` = Set variable out of range :py:exc:`~escpos.exceptions.SetVariableError`
     - `200` = Configuration not found :py:exc:`~escpos.exceptions.ConfigNotFoundError`
     - `210` = Configuration syntax error :py:exc:`~escpos.exceptions.ConfigSyntaxError`
+    - `220` = Configuration section not found :py:exc:`~escpos.exceptions.ConfigSectionMissingError`
 
 :author: `Manuel F Martinez <manpaz@bashlinux.com>`_ and others
 :organization: Bashlinux and `python-escpos <https://github.com/python-escpos>`_
@@ -211,7 +212,7 @@ class ConfigNotFoundError(Error):
 class ConfigSyntaxError(Error):
     """ The configuration file is invalid
 
-    The syntax is incorrect or there is a section missing
+    The syntax is incorrect
     Ths returncode for this exception is `210`.
     """
     def __init__(self, msg=""):
@@ -221,3 +222,17 @@ class ConfigSyntaxError(Error):
 
     def __str__(self):
         return "Configuration syntax is invalid ({msg})".format(msg=self.msg)
+
+class ConfigSectionMissingError(Error):
+    """ The configuration file is missing a section
+
+    The part of the config asked for doesn't exist in the loaded configuration
+    Ths returncode for this exception is `220`.
+    """
+    def __init__(self, msg=""):
+        Error.__init__(self, msg)
+        self.msg = msg
+        self.resultcode = 220
+
+    def __str__(self):
+        return "Configuration section is missing ({msg})".format(msg=self.msg)