Implement github trigger requirement status

This allows using a connection specific requirement on the status of the
head of a PR. A list of statuses is accepted, just like the pipeline
requirement.

Update GithubRefFilter class to be more clear that it deals with
required statuses, whereas the event filter works with the status being
provided.

Change-Id: Ib91f6527bf1d8ff5fbc6434c8adaca1cd5e1ba6d
diff --git a/tests/unit/test_github_requirements.py b/tests/unit/test_github_requirements.py
index 60bcf74..5f8f14d 100644
--- a/tests/unit/test_github_requirements.py
+++ b/tests/unit/test_github_requirements.py
@@ -49,6 +49,30 @@
     @simple_layout('layouts/requirements-github.yaml', driver='github')
     def test_trigger_require_status(self):
         "Test trigger requirement: status"
+        A = self.fake_github.openFakePullRequest('org/project1', 'master', 'A')
+        # A comment event that we will keep submitting to trigger
+        comment = A.getCommentAddedEvent('trigger me')
+        self.fake_github.emitEvent(comment)
+        self.waitUntilSettled()
+        # No status from zuul so should not be enqueued
+        self.assertEqual(len(self.history), 0)
+
+        # An error status should not cause it to be enqueued
+        A.setStatus(A.head_sha, 'error', 'null', 'null', 'check')
+        self.fake_github.emitEvent(comment)
+        self.waitUntilSettled()
+        self.assertEqual(len(self.history), 0)
+
+        # A success status goes in
+        A.setStatus(A.head_sha, 'success', 'null', 'null', 'check')
+        self.fake_github.emitEvent(comment)
+        self.waitUntilSettled()
+        self.assertEqual(len(self.history), 1)
+        self.assertEqual(self.history[0].name, 'project1-pipeline')
+
+    @simple_layout('layouts/requirements-github.yaml', driver='github')
+    def test_trigger_on_status(self):
+        "Test trigger on: status"
         A = self.fake_github.openFakePullRequest('org/project2', 'master', 'A')
 
         # An error status should not cause it to be enqueued