[modules/cmus] Re-add cmus module

Re-add a first version of the cmus module originally contributed by
@paxy97.

Still missing:
* Icon themes (status)
* On-click actions

see #23

tests/modules/test_cmus.py

@@ -0,0 +1,30 @@
+# pylint: disable=C0103,C0111
+
+import json
+import unittest
+import mock
+
+import bumblebee.input
+from bumblebee.input import I3BarInput
+from bumblebee.modules.cmus import Module
+from tests.util import MockEngine, MockConfig, assertPopen
+
+class TestCmusModule(unittest.TestCase):
+    def setUp(self):
+        self.engine = MockEngine()
+        self.module = Module(engine=self.engine, config={"config": MockConfig()})
+
+    @mock.patch("subprocess.Popen")
+    def test_read_song(self, mock_output):
+        rv = mock.Mock()
+        rv.configure_mock(**{
+            "communicate.return_value": ("out", None)
+        })
+        mock_output.return_value = rv
+        self.module.update(self.module.widgets())
+        assertPopen(mock_output, "cmus-remote -Q")
+
+    def test_widgets(self):
+        self.assertTrue(len(self.module.widgets()), 5)
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4