[core/engine] Add module loading logic

Allow the engine to load modules from the bumblebee/modules/ directory.

see #23

bumblebee/engine.py

@@ -1,5 +1,18 @@
 """Core application engine"""
 
+import importlib
+
+class Module(object):
+    """Module instance base class
+
+    Objects of this type represent the modules that
+    the user configures. Concrete module implementations
+    (e.g. CPU utilization, disk usage, etc.) derive from
+    this base class.
+    """
+    def __init__(self, engine):
+        pass
+
 class Engine(object):
     """Engine for driving the application
 
@@ -8,6 +21,19 @@ class Engine(object):
     """
     def __init__(self, config):
         self._running = True
+        self._modules = []
+        self.load_modules(config.modules())
+
+    def load_modules(self, modules):
+        """Load specified modules and return them as list"""
+        for module in modules:
+            self._modules.append(self.load_module(module["module"]))
+        return self._modules
+
+    def load_module(self, module_name):
+        """Load specified module and return it as object"""
+        module = importlib.import_module("bumblebee.modules.{}".format(module_name))
+        return getattr(module, "Module")(self)
 
     def running(self):
         """Check whether the event loop is running"""

bumblebee/modules/test.py

@@ -0,0 +1,11 @@
+# pylint: disable=C0111,R0903
+
+"""Test module"""
+
+import bumblebee.engine
+
+class Module(bumblebee.engine.Module):
+    def __init__(self, engine):
+        super(Module, self).__init__(engine)
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4

runtests.sh

@@ -2,10 +2,12 @@
 
 test=$(which nosetests)
 
-echo "testing $(python2 -V 2>&1)"
+echo "testing with $(python2 -V 2>&1)"
 python2 $test --rednose -v tests/
 
+if [ $? == 0 ]; then
 	echo
 
-echo "testing $(python3 -V 2>&1)"
+	echo "testing with $(python3 -V 2>&1)"
 	python3 $test --rednose -v tests/
+fi

tests/test_engine.py

@@ -2,12 +2,33 @@
 import unittest
 
 from bumblebee.engine import Engine
+from bumblebee.config import Config
 
 class TestEngine(unittest.TestCase):
     def setUp(self):
-        self.engine = Engine(None)
+        self.engine = Engine(Config())
+        self.testModule = "test"
+        self.testModuleSpec = "bumblebee.modules.{}".format(self.testModule)
+        self.testModules = [
+            { "module": "test", "name": "a" },
+            { "module": "test", "name": "b" },
+        ]
 
     def test_stop(self):
         self.assertTrue(self.engine.running())
         self.engine.stop()
         self.assertFalse(self.engine.running())
+
+    def test_load_module(self):
+        module = self.engine.load_module(self.testModule)
+        self.assertEquals(module.__module__, self.testModuleSpec)
+
+    def test_load_modules(self):
+        modules = self.engine.load_modules(self.testModules)
+        self.assertEquals(len(modules), len(self.testModules))
+        self.assertEquals(
+            [ module.__module__ for module in modules ],
+            [ self.testModuleSpec for module in modules ]
+        )
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4