[gitlab] approvals: fix error with community edition

'approvals_left' key is not present when 'Required Merge Request
Approvals' feature isn't available. With enterprise edition,
'approved' key can not be used since the related value is always true
when 'approvals_required' is equal to zero.

The exception was:

    Traceback (most recent call last):
      File "zuul/driver/gitlab/gitlabconnection.py", line 240, in run
	self._handleEvent()
      File "zuul/driver/gitlab/gitlabconnection.py", line 230, in _handleEvent
	event=event)
      File "driver/gitlab/gitlabconnection.py", line 510, in _getChange
	self._updateChange(change, event)
      File "driver/gitlab/gitlabconnection.py", line 521, in _updateChange
	change.project.name, change.number, event=event)
      File "zuul/driver/gitlab/gitlabconnection.py", line 560, in getMR
	mr['approved'] = mr_approval_status['approvals_left'] == 0
    KeyError: 'approvals_left'

Change-Id: I07303ae3309937046b69afe18e9e183853fd448f

1 files changed, 23 insertions, 0 deletions

diff --git a/tests/unit/test_gitlab_driver.py b/tests/unit/test_gitlab_driver.py
index 11edaf0c4..009df0a7f 100644
--- a/tests/unit/test_gitlab_driver.py
+++ b/tests/unit/test_gitlab_driver.py
@@ -560,6 +560,29 @@ class TestGitlabDriver(ZuulTestCase):
         self.assertEqual(1, len(self.history))
 
     @simple_layout('layouts/requirements-gitlab.yaml', driver='gitlab')
+    def test_approval_require_community_edition(self):
+
+        with self.fake_gitlab.enable_community_edition():
+            A = self.fake_gitlab.openFakeMergeRequest(
+                'org/project2', 'master', 'A')
+
+            self.fake_gitlab.emitEvent(A.getMergeRequestOpenedEvent())
+            self.waitUntilSettled()
+            self.assertEqual(0, len(self.history))
+
+            A.approved = True
+
+            self.fake_gitlab.emitEvent(A.getMergeRequestUpdatedEvent())
+            self.waitUntilSettled()
+            self.assertEqual(1, len(self.history))
+
+            A.approved = False
+
+            self.fake_gitlab.emitEvent(A.getMergeRequestUpdatedEvent())
+            self.waitUntilSettled()
+            self.assertEqual(1, len(self.history))
+
+    @simple_layout('layouts/requirements-gitlab.yaml', driver='gitlab')
     def test_label_require(self):
 
         A = self.fake_gitlab.openFakeMergeRequest(