[core/theme] Add support for default -> prefix/suffix in themes

Themes can now define default prefix and suffix strings.

see #23

tests/test_theme.py

@@ -3,15 +3,18 @@
 import unittest
 from bumblebee.theme import Theme
 from bumblebee.error import ThemeLoadError
+from tests.util import MockWidget
 
 class TestTheme(unittest.TestCase):
     def setUp(self):
         self.nonexistentThemeName = "no-such-theme"
         self.invalidThemeName = "invalid"
+        self.validThemeName = "solarized-powerline"
+        self.someWidget = MockWidget("foo")
 
     def test_load_valid_theme(self):
         try:
-            Theme("solarized-powerline")
+            Theme(self.validThemeName)
         except Exception as e:
             self.fail(e)
 
@@ -23,4 +26,14 @@ class TestTheme(unittest.TestCase):
         with self.assertRaises(ThemeLoadError):
             Theme(self.invalidThemeName)
 
+    def test_prefix(self):
+        theme = Theme(self.validThemeName)
+        theme.loads('{"defaults": { "prefix": "test" }}')
+        self.assertEquals(theme.prefix(self.someWidget), "test")
+
+    def test_suffix(self):
+        theme = Theme(self.validThemeName)
+        theme.loads('{"defaults": { "suffix": "test" }}')
+        self.assertEquals(theme.suffix(self.someWidget), "test")
+
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