Test canMerge also with checks api

There is no test case for the checks api that validates that canMerge
also takes check runs into account if they are required. To test this
we can simply add and trigger a gate pipeline after the reporting test
case.

Change-Id: Icb7e738a5f495e63b70c9a0937087909ff6422e8

tests/fixtures/layouts/reporting-github.yaml

@@ -97,6 +97,21 @@
       github:
         check: failure
 
+- pipeline:
+    name: gate
+    manager: dependent
+    trigger:
+      github:
+        - event: pull_request
+          action: comment
+          comment: merge me
+    success:
+      github:
+        status: success
+        merge: true
+    failure:
+      github: {}
+
 - job:
     name: base
     parent: null
@@ -129,3 +144,6 @@
     checks-api-reporting:
       jobs:
         - project-test1
+    gate:
+      jobs:
+        - project-test1

tests/unit/test_github_driver.py

@@ -1597,6 +1597,10 @@ class TestGithubAppDriver(ZuulGithubAppTestCase):
         """Using the checks API only works with app authentication"""
         project = "org/project3"
         github = self.fake_github.getGithubClient(None)
+        repo = github.repo_from_project('org/project3')
+        repo._set_branch_protection(
+            'master', contexts=['tenant-one/checks-api-reporting',
+                                'tenant-one/gate'])
 
         # pipeline reports pull request status both on start and success
         self.executor_server.hold_jobs_in_build = True
@@ -1640,6 +1644,11 @@ class TestGithubAppDriver(ZuulGithubAppTestCase):
         )
         self.assertIsNotNone(check_run["completed_at"])
 
+        # Tell gate to merge to test checks requirements
+        self.fake_github.emitEvent(A.getCommentAddedEvent('merge me'))
+        self.waitUntilSettled()
+        self.assertTrue(A.is_merged)
+
     @simple_layout("layouts/reporting-github.yaml", driver="github")
     def test_update_non_existing_check_run(self):
         project = "org/project3"