Fix audit creation with no name and no goal or audit_template

Currently, in that case it was failing because watcher tried to create a
name based on a goal automatically and the goal is not defined.

This patch is moving the check for goal specification in the audit
creation call earlier, and if there is not goal defined, it returns an
invalid call error.

This patch is also modifying the existing error for this case to check
the expected behavior.

Closes-Bug: #2110947

Change-Id: I6f3d73b035e8081e86ce82c205498432f0e0fc33

releasenotes/notes/bug-2110947.yaml

@@ -0,0 +1,10 @@
+---
+fixes:
+  - |
+     Previously, when users attempted to create a new audit without providing
+     a name and a goal or an audit template, the API returned error 500 and an
+     incorrect error message was displayed.
+
+     Now, Watcher displays a helpful message and returns HTTP error 400.
+
+     For more info see: https://bugs.launchpad.net/watcher/+bug/2110947

watcher/api/controllers/v1/audit.py

@@ -114,6 +114,11 @@ class AuditPostType(wtypes.Base):
         if self.audit_type not in audit_type_values:
             raise exception.AuditTypeNotFound(audit_type=self.audit_type)
 
+        if not self.audit_template_uuid and not self.goal:
+            message = _(
+                'A valid goal or audit_template_id must be provided')
+            raise exception.Invalid(message)
+
         if (self.audit_type == objects.audit.AuditType.ONESHOT.value and
                 self.interval not in (wtypes.Unset, None)):
             raise exception.AuditIntervalNotAllowed(audit_type=self.audit_type)
@@ -612,11 +617,6 @@ class AuditsController(rest.RestController):
         if self.from_audits:
             raise exception.OperationNotPermitted
 
-        if not audit._goal_uuid:
-            raise exception.Invalid(
-                message=_('A valid goal_id or audit_template_id '
-                          'must be provided'))
-
         strategy_uuid = audit.strategy_uuid
         no_schema = True
         if strategy_uuid is not None:

watcher/tests/api/v1/test_audits.py

@@ -1002,10 +1002,11 @@ class TestPost(api_base.FunctionalTest):
             expect_errors=True,
             headers={'OpenStack-API-Version': 'infra-optim 1.2'})
         self.assertEqual('application/json', response.content_type)
-        # (amoralej) this should return HTTP error 400 with a proper message.
-        # I am adding this test to show the bug here, I will switch it to the
-        # expected error in the fixing patch.
-        self.assertEqual(HTTPStatus.INTERNAL_SERVER_ERROR, response.status_int)
+        self.assertEqual(HTTPStatus.BAD_REQUEST, response.status_int)
+        expected_msg = 'A valid goal or audit_template_id must be provided'
+        self.assertTrue(response.json['error_message'])
+        self.assertIn(expected_msg, response.json['error_message'])
+        assert not mock_trigger_audit.called
 
 
 class TestDelete(api_base.FunctionalTest):