Add ability to send messages about progress

With this patch, Pungi can invoke an arbitrary command on various
moments of the compose process. The invoked command can the decide on
what message to send (and using what messaging system).

The actual command is specified in the config file.

There is a script provided that sends the messages via fedmsg.

The documentation is updated to have details about the new config option
as well as the interface for the messaging script.

Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

tests/test_notifier.py

@@ -0,0 +1,82 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+import json
+import mock
+import os
+import sys
+import unittest
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))
+
+from pungi.notifier import PungiNotifier
+
+
+class TestNotifier(unittest.TestCase):
+    def test_incorrect_config(self):
+        compose = mock.Mock(
+            conf={'notification_script': [1, 2]}
+        )
+
+        n = PungiNotifier(compose)
+        with self.assertRaises(ValueError) as err:
+            n.validate()
+            self.assertIn('notification_script', err.message)
+
+    @mock.patch('kobo.shortcuts.run')
+    def test_invokes_script(self, run):
+        compose = mock.Mock(
+            compose_id='COMPOSE_ID',
+            conf={'notification_script': 'run-notify'},
+            paths=mock.Mock(
+                compose=mock.Mock(
+                    topdir=mock.Mock(return_value='/a/b')
+                )
+            )
+        )
+
+        run.return_value = (0, None)
+
+        n = PungiNotifier(compose)
+        data = {'foo': 'bar', 'baz': 'quux'}
+        n.send('cmd', **data)
+
+        data['compose_id'] = 'COMPOSE_ID'
+        run.assert_called_once_with(('run-notify', 'cmd'),
+                                    stdin_data=json.dumps(data),
+                                    can_fail=True, return_stdout=False, workdir='/a/b')
+
+    @mock.patch('kobo.shortcuts.run')
+    def test_does_not_run_without_config(self, run):
+        compose = mock.Mock(conf={})
+
+        n = PungiNotifier(compose)
+        n.send('cmd', foo='bar', baz='quux')
+        self.assertFalse(run.called)
+
+    @mock.patch('kobo.shortcuts.run')
+    def test_logs_warning_on_failure(self, run):
+        compose = mock.Mock(
+            compose_id='COMPOSE_ID',
+            log_warning=mock.Mock(),
+            conf={'notification_script': 'run-notify'},
+            paths=mock.Mock(
+                compose=mock.Mock(
+                    topdir=mock.Mock(return_value='/a/b')
+                )
+            )
+        )
+
+        run.return_value = (1, None)
+
+        n = PungiNotifier(compose)
+        n.send('cmd')
+
+        run.assert_called_once_with(('run-notify', 'cmd'),
+                                    stdin_data=json.dumps({'compose_id': 'COMPOSE_ID'}),
+                                    can_fail=True, return_stdout=False, workdir='/a/b')
+        self.assertTrue(compose.log_warning.called)
+
+
+if __name__ == "__main__":
+    unittest.main()