github: use change.message in squahsed commit message

So far, github use the subject of the first change in the commit
message body. This is most of the time redundant with the PR title.
Ths idea is to use instead the change body.

Change-Id: I9a2bc8aa3ff60a28b2ed62a4ee5fa9f7a2c9dcda

tests/base.py

@@ -1798,7 +1798,7 @@ class FakeGithubPullRequest(object):
 
     def __init__(self, github, number, project, branch,
                  subject, upstream_root, files=[], number_of_commits=1,
-                 writers=[], body=None, draft=False):
+                 writers=[], body=None, body_text=None, draft=False):
         """Creates a new PR with several commits.
         Sends an event about opened PR."""
         self.github = github
@@ -1808,6 +1808,7 @@ class FakeGithubPullRequest(object):
         self.branch = branch
         self.subject = subject
         self.body = body
+        self.body_text = body_text
         self.draft = draft
         self.number_of_commits = 0
         self.upstream_root = upstream_root
@@ -2200,11 +2201,11 @@ class FakeGithubConnection(githubconnection.GithubConnection):
         self.zuul_web_port = port
 
     def openFakePullRequest(self, project, branch, subject, files=[],
-                            body=None, draft=False):
+                            body=None, body_text=None, draft=False):
         self.pr_number += 1
         pull_request = FakeGithubPullRequest(
             self, self.pr_number, project, branch, subject, self.upstream_root,
-            files=files, body=body, draft=draft)
+            files=files, body=body, body_text=body_text, draft=draft)
         self.pull_requests[self.pr_number] = pull_request
         return pull_request
 

tests/fakegithub.py

@@ -521,6 +521,7 @@ class FakePull(object):
             },
             'merged': pr.is_merged,
             'body': pr.body,
+            'body_text': pr.body_text,
             'changed_files': len(pr.files),
             'labels': [{'name': l} for l in pr.labels]
         }

tests/unit/test_github_driver.py

@@ -630,12 +630,18 @@ class TestGithubDriver(ZuulTestCase):
     def test_report_pull_merge(self):
         # pipeline merges the pull request on success
         A = self.fake_github.openFakePullRequest('org/project', 'master',
-                                                 'PR title')
+                                                 'PR title',
+                                                 body='I shouldnt be seen',
+                                                 body_text='PR body')
         self.fake_github.emitEvent(A.getCommentAddedEvent('merge me'))
         self.waitUntilSettled()
         self.assertTrue(A.is_merged)
         self.assertThat(A.merge_message,
-                        MatchesRegex(r'.*PR title.*', re.DOTALL))
+                        MatchesRegex(r'.*PR title\n\nPR body.*', re.DOTALL))
+        self.assertThat(A.merge_message,
+                        Not(MatchesRegex(
+                            r'.*I shouldnt be seen.*',
+                            re.DOTALL)))
         self.assertEqual(len(A.comments), 0)
 
         # pipeline merges the pull request on success after failure

zuul/driver/github/githubconnection.py

@@ -1374,6 +1374,7 @@ class GithubConnection(BaseConnection):
             else:
                 message = change.title
         change.message = message
+        change.body_text = change.pr.get("body_text")
 
         # Note(tobiash): The updated_at timestamp is a moving target that is
         # not bound to the pull request 'version' we can solve that by just not

zuul/driver/github/githubmodel.py

@@ -34,6 +34,7 @@ class PullRequest(Change):
         self.pr = None
         self.updated_at = None
         self.title = None
+        self.body_text = None
         self.reviews = []
         self.files = []
         self.labels = []

zuul/driver/github/githubreporter.py

@@ -265,10 +265,12 @@ class GithubReporter(BaseReporter):
                                         zuul_event_id=item.event)
 
     def _formatMergeMessage(self, change):
-        message = ''
+        message = []
-
         if change.title:
-            message += change.title
+            message.append(change.title)
+        if change.body_text:
+            message.append(change.body_text)
+        merge_message = "\n\n".join(message)
 
         if change.reviews:
             review_users = []
@@ -276,10 +278,10 @@ class GithubReporter(BaseReporter):
                 name = r['by']['username']
                 email = r['by']['email']
                 review_users.append('Reviewed-by: {} <{}>'.format(name, email))
-            message += '\n\n'
+            merge_message += '\n\n'
-            message += '\n'.join(review_users)
+            merge_message += '\n'.join(review_users)
 
-        return message
+        return merge_message
 
     def getSubmitAllowNeeds(self):
         """Get a list of code review labels that are allowed to be