diff --git a/bumblebee/engine.py b/bumblebee/engine.py
index 3c07d98..e2b4826 100644
--- a/bumblebee/engine.py
+++ b/bumblebee/engine.py
@@ -55,10 +55,12 @@ class Engine(object):
         while self.running():
             widgets = []
             for module in self._modules:
-                widgets += module.widgets()
-            self._output.draw(widgets)
+                module_widgets = module.widgets()
+                widgets += module_widgets if isinstance(module_widgets, list) else [module_widgets]
+            self._output.draw(widgets=widgets, engine=self)
             self._output.flush()
-            time.sleep(1)
+            if self.running():
+                time.sleep(1)
 
         self._output.stop()
 
diff --git a/bumblebee/modules/cpu.py b/bumblebee/modules/cpu.py
new file mode 100644
index 0000000..ecc2376
--- /dev/null
+++ b/bumblebee/modules/cpu.py
@@ -0,0 +1,18 @@
+# pylint: disable=C0111,R0903
+
+"""Displays CPU utilization across all CPUs."""
+
+import psutil
+import bumblebee.engine
+
+class Module(bumblebee.engine.Module):
+    def __init__(self, engine):
+        super(Module, self).__init__(engine)
+        self._utilization = psutil.cpu_percent(percpu=False)
+
+    def widgets(self):
+        self._utilization = psutil.cpu_percent(percpu=False)
+
+        return bumblebee.output.Widget(full_text="{:05.02f}%".format(self._utilization))
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4
diff --git a/bumblebee/modules/test.py b/bumblebee/modules/test.py
index 79c0ec9..94b99c4 100644
--- a/bumblebee/modules/test.py
+++ b/bumblebee/modules/test.py
@@ -9,6 +9,6 @@ class Module(bumblebee.engine.Module):
         super(Module, self).__init__(engine)
 
     def widgets(self):
-        return []
+        return bumblebee.output.Widget(full_text="test")
 
 # vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4
diff --git a/bumblebee/output.py b/bumblebee/output.py
index 96ebe0b..bd05450 100644
--- a/bumblebee/output.py
+++ b/bumblebee/output.py
@@ -5,6 +5,15 @@
 import sys
 import json
 
+class Widget(object):
+    """Represents a single visible block in the status bar"""
+    def __init__(self, full_text):
+        self._full_text = full_text
+
+    def full_text(self):
+        """Retrieve the full text to display in the widget"""
+        return self._full_text
+
 class I3BarOutput(object):
     """Manage output according to the i3bar protocol"""
     def __init__(self):
@@ -18,14 +27,14 @@ class I3BarOutput(object):
         """Finish i3bar protocol"""
         sys.stdout.write("]\n")
 
-    def draw(self, widgets):
+    def draw(self, widgets, engine=None):
         """Draw a number of widgets"""
         if not isinstance(widgets, list):
             widgets = [widgets]
         result = []
         for widget in widgets:
             result.append({
-                u"full_text": widget.text()
+                u"full_text": widget.full_text()
             })
         sys.stdout.write(json.dumps(result))
 
diff --git a/tests/modules/__init__.py b/tests/modules/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/modules/test_cpu.py b/tests/modules/test_cpu.py
new file mode 100644
index 0000000..9c3be94
--- /dev/null
+++ b/tests/modules/test_cpu.py
@@ -0,0 +1,16 @@
+# pylint: disable=C0103,C0111
+
+import unittest
+
+from bumblebee.modules.cpu import Module
+from tests.util import assertWidgetAttributes
+
+class TestCPUModule(unittest.TestCase):
+    def setUp(self):
+        self.module = Module(None)
+
+    def test_widgets(self):
+        widget = self.module.widgets()
+        assertWidgetAttributes(self, widget)
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4
diff --git a/tests/test_engine.py b/tests/test_engine.py
index 2cb5ea3..03f8334 100644
--- a/tests/test_engine.py
+++ b/tests/test_engine.py
@@ -1,13 +1,17 @@
 # pylint: disable=C0103,C0111
+
 import unittest
 
 from bumblebee.error import ModuleLoadError
 from bumblebee.engine import Engine
 from bumblebee.config import Config
 
+from tests.util import MockOutput
+
 class TestEngine(unittest.TestCase):
     def setUp(self):
-        self.engine = Engine(Config())
+        self.engine = Engine(config=Config(), output=MockOutput())
+        self.singleWidgetModule = [{"module": "test"}]
         self.testModule = "test"
         self.invalidModule = "no-such-module"
         self.testModuleSpec = "bumblebee.modules.{}".format(self.testModule)
@@ -41,4 +45,11 @@ class TestEngine(unittest.TestCase):
             [self.testModuleSpec for module in modules]
         )
 
+    def test_run(self):
+        self.engine.load_modules(self.singleWidgetModule)
+        try:
+            self.engine.run()
+        except Exception as e:
+            self.fail(e)
+
 # vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4
diff --git a/tests/test_i3baroutput.py b/tests/test_i3baroutput.py
index c8e01e0..4a277ae 100644
--- a/tests/test_i3baroutput.py
+++ b/tests/test_i3baroutput.py
@@ -32,14 +32,14 @@ class TestI3BarOutput(unittest.TestCase):
     def test_draw_single_widget(self, stdout):
         self.output.draw(self.someWidget)
         result = json.loads(stdout.getvalue())[0]
-        self.assertEquals(result["full_text"], self.someWidget.text())
+        self.assertEquals(result["full_text"], self.someWidget.full_text())
 
     @mock.patch("sys.stdout", new_callable=StringIO)
     def test_draw_multiple_widgets(self, stdout):
         self.output.draw([self.someWidget, self.someWidget])
         result = json.loads(stdout.getvalue())
         for res in result:
-            self.assertEquals(res["full_text"], self.someWidget.text())
+            self.assertEquals(res["full_text"], self.someWidget.full_text())
 
     @mock.patch("sys.stdout", new_callable=StringIO)
     def test_flush(self, stdout):
diff --git a/tests/util.py b/tests/util.py
index 202da49..542b220 100644
--- a/tests/util.py
+++ b/tests/util.py
@@ -1,10 +1,29 @@
 # pylint: disable=C0103,C0111
 
+from bumblebee.output import Widget
+
+def assertWidgetAttributes(test, widget):
+    test.assertTrue(isinstance(widget, Widget))
+    test.assertTrue(hasattr(widget, "full_text"))
+
+class MockOutput(object):
+    def start(self):
+        pass
+
+    def stop(self):
+        pass
+
+    def draw(self, widgets, engine):
+        engine.stop()
+
+    def flush(self):
+        pass
+
 class MockWidget(object):
     def __init__(self, text):
         self._text = text
 
-    def text(self):
+    def full_text(self):
         return self._text
 
 # vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4