Add BaseOutput and DummyOutput

mopidy/outputs/base.py

@@ -0,0 +1,16 @@
+class BaseOutput(object):
+    """
+    Base class for audio outputs.
+    """
+
+    def start(self):
+        """Start the output."""
+        pass
+
+    def destroy(self):
+        """Destroy the output."""
+        pass
+
+    def process_message(self, message):
+        """Process messages with the output as destination."""
+        raise NotImplementedError

mopidy/outputs/dummy.py

@@ -0,0 +1,24 @@
+from mopidy.outputs.base import BaseOutput
+
+class DummyOutput(BaseOutput):
+    """
+    Audio output used for testing.
+    """
+
+    #: For testing. :class:`True` if :meth:`start` has been called.
+    start_called = False
+
+    #: For testing. :class:`True` if :meth:`destroy` has been called.
+    destroy_called = False
+
+    #: For testing. Contains all messages :meth:`process_message` has received.
+    messages = []
+
+    def start(self):
+        self.start_called = True
+
+    def destroy(self):
+        self.destroy_called = True
+
+    def process_message(self, message):
+        self.messages.append(message)