danger: check that original MR has been merged

When checking a backport MR, ensure that the original MR has been merged
already. This is vital for followup checks that verify commit IDs from
original commits are present in backport commit messages.

(cherry picked from commit 89530f1a1cb2e90b5368605fc317eaed35bf9d1f)

diff --git a/dangerfile.py b/dangerfile.py
index a5fb883c8f377bb2809f88d45b0e703267b971e0..da41d6e9f7c2c6c099bbb0f1f185d497a42eccfc 100644 (file)
--- a/dangerfile.py
+++ b/dangerfile.py
@@ -9,8 +9,11 @@
 # information regarding copyright ownership.
 ############################################################################
 
+import os
 import re
 
+import gitlab
+
 # Helper functions and variables
 
 def added_lines(target_branch, paths):
@@ -37,6 +40,12 @@ target_branch = danger.gitlab.mr.target_branch
 is_backport = "Backport" in mr_labels or "Backport::Partial" in mr_labels
 is_full_backport = is_backport and "Backport::Partial" not in mr_labels
 
+gl = gitlab.Gitlab(
+    url=f"https://{os.environ['CI_SERVER_HOST']}",
+    private_token=os.environ["DANGER_GITLAB_API_TOKEN"],
+)
+proj = gl.projects.get(os.environ["CI_PROJECT_ID"])
+
 ###############################################################################
 # COMMIT MESSAGES
 ###############################################################################
@@ -131,6 +140,8 @@ if not danger.gitlab.mr.milestone:
 # * The Backport MR doesn't have target branch in the merge request title.
 #
 # * The Backport MR doesn't link to the original MR is its description.
+#
+# * The original MR linked to from Backport MR hasn't been merged.
 
 BACKPORT_OF_RE = re.compile(
     r"Backport\s+of.*(merge_requests/|!)([0-9]+)", flags=re.IGNORECASE
@@ -155,6 +166,14 @@ if is_backport:
             "Backport MRs must link to the original MR. Please put "
             "`Backport of MR !XXXX` in the MR description."
         )
+    else:  # backport MR is linked to original MR
+        original_mr_id = backport_desc.groups()[1]
+        original_mr = proj.mergerequests.get(original_mr_id)
+        if original_mr.state != "merged":
+            fail(
+                f"Original MR !{original_mr_id} has not been merged. "
+                "Please re-run `danger` check once it's merged."
+            )
 if not is_backport and not version_labels:
     fail(
         "If this merge request is a backport, set the *Backport* label and "