Basic icon module tests

Calling `get_from_name()` with no parameters, should return the pixbuf
object through `load_icon()` and default parameters.

requirements.txt

@@ -1,2 +1,3 @@
 lxml
 coveralls
+mock

tests/utils/test_icon.py

@@ -0,0 +1,22 @@
+import unittest
+import mock
+
+from gi.repository import GdkPixbuf
+from ubuntucleaner.utils.icon import get_from_name, DEFAULT_SIZE
+
+
+class TestIconModule(unittest.TestCase):
+
+    def test_get_from_name(self):
+        """
+        Calling with no parameters should return the pixbuf object through `load_icon()`
+        and default parameters.
+        """
+        m_pixbuf = mock.Mock(spec=GdkPixbuf.Pixbuf, get_height=lambda: DEFAULT_SIZE)
+        with mock.patch("ubuntucleaner.utils.icon.Gtk.IconTheme.load_icon") as m_load_icon:
+            m_load_icon.return_value = m_pixbuf
+            pixbuf = get_from_name()
+        self.assertEqual(
+            m_load_icon.call_args_list, [mock.call("gtk-execute", 24, 0)]
+        )
+        self.assertEqual(pixbuf, m_pixbuf)