[modules/brighness] Re-enable brightness module

Add a module for reporting, increasing and decreasing the brightness of
a display.

see #23

tests/modules/test_brightness.py

@@ -0,0 +1,72 @@
+# pylint: disable=C0103,C0111
+
+import json
+import unittest
+import mock
+
+import bumblebee.input
+from bumblebee.input import I3BarInput
+from bumblebee.modules.brightness import Module
+from tests.util import MockEngine, MockConfig, assertPopen
+
+class TestBrightnessModule(unittest.TestCase):
+    def setUp(self):
+        self.engine = MockEngine()
+        self.engine.input = I3BarInput()
+        self.engine.input.need_event = True
+        self.config = MockConfig()
+        self.module = Module(engine=self.engine, config={ "config": self.config })
+        for widget in self.module.widgets():
+            widget.link_module(self.module)
+
+    @mock.patch("sys.stdout")
+    def test_format(self, mock_output):
+        for widget in self.module.widgets():
+            self.assertEquals(len(widget.full_text()), len("100%"))
+
+    @mock.patch("select.select")
+    @mock.patch("subprocess.Popen")
+    @mock.patch("sys.stdin")
+    def test_wheel_up(self, mock_input, mock_output, mock_select):
+        mock_input.readline.return_value = json.dumps({
+            "name": self.module.id,
+            "button": bumblebee.input.WHEEL_UP,
+            "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, "xbacklight +2%")
+
+    @mock.patch("select.select")
+    @mock.patch("subprocess.Popen")
+    @mock.patch("sys.stdin")
+    def test_wheel_down(self, mock_input, mock_output, mock_select):
+        mock_input.readline.return_value = json.dumps({
+            "name": self.module.id,
+            "button": bumblebee.input.WHEEL_DOWN,
+            "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, "xbacklight -2%")
+
+    @mock.patch("select.select")
+    @mock.patch("subprocess.Popen")
+    @mock.patch("sys.stdin")
+    def test_custom_step(self, mock_input, mock_output, mock_select):
+        self.config.set("brightness.step", "10")
+        module = Module(engine=self.engine, config={ "config": self.config })
+        mock_input.readline.return_value = json.dumps({
+            "name": module.id,
+            "button": bumblebee.input.WHEEL_DOWN,
+            "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, "xbacklight -10%")