[modules/disk] Re-enable disk usage module

Add a module that shows the disk usage for various paths and opens
nautilus on that path whenever it is clicked.

see #23

tests/modules/test_disk.py

@@ -0,0 +1,36 @@
+# pylint: disable=C0103,C0111
+
+import json
+import unittest
+import mock
+
+import bumblebee.input
+from bumblebee.input import I3BarInput
+from bumblebee.modules.disk import Module
+from tests.util import MockEngine, MockConfig, assertPopen
+
+class TestDiskModule(unittest.TestCase):
+    def setUp(self):
+        self.engine = MockEngine()
+        self.engine.input = I3BarInput()
+        self.engine.input.need_event = True
+        self.config = MockConfig()
+        self.config.set("disk.path", "somepath")
+        self.module = Module(engine=self.engine, config={"config": self.config})
+
+    @mock.patch("select.select")
+    @mock.patch("subprocess.Popen")
+    @mock.patch("sys.stdin")
+    def test_leftclick(self, mock_input, mock_output, mock_select):
+        mock_input.readline.return_value = json.dumps({
+            "name": self.module.id,
+            "button": bumblebee.input.LEFT_MOUSE,
+            "instance": None
+        })
+        mock_select.return_value = (1,2,3)
+        self.engine.input.start()
+        self.engine.input.stop()
+        mock_input.readline.assert_any_call()
+        assertPopen(mock_output, "nautilus {}".format(self.module.parameter("path")))
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4