tests: Test existing exception classes

tests/exceptions_test.py

@@ -0,0 +1,21 @@
+from __future__ import unicode_literals
+
+from mopidy import exceptions
+
+from tests import unittest
+
+
+class ExceptionsTest(unittest.TestCase):
+    def test_exception_can_include_message_string(self):
+        exc = exceptions.MopidyException('foo')
+
+        self.assertEqual(exc.message, 'foo')
+        self.assertEqual(str(exc), 'foo')
+
+    def test_settings_error_is_a_mopidy_exception(self):
+        self.assert_(issubclass(
+            exceptions.SettingsError, exceptions.MopidyException))
+
+    def test_optional_dependency_error_is_a_mopidy_exception(self):
+        self.assert_(issubclass(
+            exceptions.OptionalDependencyError, exceptions.MopidyException))