Merge branch 'master' into issue/426

Author: pengale

juju/application.py

@@ -17,6 +17,7 @@
 import logging
 
 from . import model, tag
+from .status import derive_status
 from .annotationhelper import _get_annotations, _set_annotations
 from .client import client
 from .errors import JujuError
@@ -76,7 +77,14 @@ def status(self):
         """Get the application status, as set by the charm's leader.
 
         """
-        return self.safe_data['status']['current']
+        status = self.safe_data['status']['current']
+        if status == 'unset':
+            unit_status = []
+            for unit in self.units:
+                unit_status.append(unit.workload_status)
+            return derive_status(unit_status)
+
+        return status
 
     @property
     def status_message(self):

juju/status.py

@@ -0,0 +1,28 @@
+""" derive_status is used to determine the application status from a set of unit
+status values.
+
+:param statues: list of known unit workload statues
+
+"""
+
+
+def derive_status(statues):
+    current = 'unknown'
+    for status in statues:
+        if status in serverities and serverities[status] > serverities[current]:
+            current = status
+    return current
+
+
+""" serverities holds status values with a severity measure.
+Status values with higher severity are used in preference to others.
+"""
+serverities = {
+    'error': 100,
+    'blocked': 90,
+    'waiting': 80,
+    'maintenance': 70,
+    'active': 60,
+    'terminated': 50,
+    'unknown': 40
+}

tests/integration/test_application.py

@@ -45,6 +45,21 @@ async def test_action(event_loop):
         assert 'backup' in actions.keys()
 
 
+@base.bootstrapped
+@pytest.mark.asyncio
+async def test_status(event_loop):
+
+    async with base.CleanModel() as model:
+        app = await model.deploy(
+            'ubuntu-0',
+            application_name='ubuntu',
+            series='trusty',
+            channel='stable',
+        )
+
+        assert app.status != 'unset'
+
+
 @base.bootstrapped
 @pytest.mark.asyncio
 async def test_add_units(event_loop):

tests/unit/test_status.py

@@ -0,0 +1,23 @@
+import unittest
+
+
+from juju.status import derive_status
+from random import sample
+
+
+class TestStatus(unittest.TestCase):
+    def test_derive_status_with_empty_list(self):
+        result = derive_status([])
+        self.assertEqual(result, 'unknown')
+
+    def test_derive_status_with_unknown(self):
+        result = derive_status(['unknown'])
+        self.assertEqual(result, 'unknown')
+
+    def test_derive_status_with_invalid(self):
+        result = derive_status(['boom'])
+        self.assertEqual(result, 'unknown')
+
+    def test_derive_status_with_highest_value(self):
+        result = derive_status(sample(['error', 'active', 'terminated'], 3))
+        self.assertEqual(result, 'error')