[modules/traffic] compute theme.minwidth based on traffic.format

tests/modules/test_traffic.py

@@ -0,0 +1,23 @@
+import mock
+import unittest
+
+import tests.mocks as mocks
+
+from bumblebee.modules.traffic import Module
+
+class TestTrafficModule(unittest.TestCase):
+    def setUp(self):
+        mocks.setup_test(self, Module)
+
+    def test_default_format(self):
+        self.assertEqual(self.module._format, "{:.2f}")
+
+    def test_get_minwidth_str(self):
+        # default value (two digits after dot)
+        self.assertEqual(self.module.get_minwidth_str(), "1000.00MB")
+        # integer value
+        self.module._format = "{:.0f}"
+        self.assertEqual(self.module.get_minwidth_str(), "1000MB")
+        # just one digit after dot
+        self.module._format = "{:.1f}"
+        self.assertEqual(self.module.get_minwidth_str(), "1000.0MB")