Merge lp:~stub/charm-helpers/fix-executution-environment into lp:charm-helpers

[Stuart Bishop]

execution_environment() explodes if invoked from a non-relation hook. Stop this happening by only adding the current relation context if there actually is current relation context.

Now we can call write_file() in an install hook.

=== modified file 'charmhelpers/core/hookenv.py'
--- charmhelpers/core/hookenv.py	2013-06-28 17:16:25 +0000
+++ charmhelpers/core/hookenv.py	2013-06-28 17:16:25 +0000
@@ -108,11 +108,12 @@
     """A convenient bundling of the current execution context"""
     context = {}
     context['conf'] = config()
-    context['reltype'] = relation_type()
-    context['relid'] = relation_id()
+    if relation_id():
+        context['reltype'] = relation_type()
+        context['relid'] = relation_id()
+        context['rel'] = relation_get()
     context['unit'] = local_unit()
     context['rels'] = relations()
-    context['rel'] = relation_get()
     context['env'] = os.environ
     return context
 
 
=== modified file 'tests/core/test_hookenv.py'
--- tests/core/test_hookenv.py	2013-06-28 17:16:25 +0000
+++ tests/core/test_hookenv.py	2013-06-28 17:16:25 +0000
@@ -496,6 +496,34 @@
             'env': 'some-environment',
         })
 
+    @patch('charmhelpers.core.hookenv.config')
+    @patch('charmhelpers.core.hookenv.relation_type')
+    @patch('charmhelpers.core.hookenv.local_unit')
+    @patch('charmhelpers.core.hookenv.relation_id')
+    @patch('charmhelpers.core.hookenv.relations')
+    @patch('charmhelpers.core.hookenv.relation_get')
+    @patch('charmhelpers.core.hookenv.os')
+    def test_gets_execution_environment_no_relation(
+        self, os_, relations_get, relations, relation_id,
+        local_unit, relation_type, config):
+        config.return_value = 'some-config'
+        relation_type.return_value = 'some-type'
+        local_unit.return_value = 'some-unit'
+        relation_id.return_value = None
+        relations.return_value = 'all-relations'
+        relations_get.return_value = 'some-relations'
+        os_.environ = 'some-environment'
+
+        result = hookenv.execution_environment()
+
+        self.assertEqual(result, {
+            'conf': 'some-config',
+            'unit': 'some-unit',
+            'rels': 'all-relations',
+            'env': 'some-environment',
+        })
+
+
     @patch('charmhelpers.core.hookenv.os')
     def test_gets_the_relation_id(self, os_):
         os_.environ = {