fix: use POST method and return dict in `cancel_merge_when_pipeline_succeeds()` (#2350)

* Call was incorrectly using a `PUT` method when should have used a
    `POST` method.
  * Changed return type to a `dict` as GitLab only returns
    {'status': 'success'} on success. Since the function didn't work
    previously, this should not impact anyone.
  * Updated the test fixture `merge_request` to add ability to create
    a pipeline.
  * Added functional test for `mr.cancel_merge_when_pipeline_succeeds()`

Fixes: #2349

2 files changed, 32 insertions, 1 deletions

diff --git a/tests/functional/api/test_merge_requests.py b/tests/functional/api/test_merge_requests.py
index 75afb08..56ee7bc 100644
--- a/tests/functional/api/test_merge_requests.py
+++ b/tests/functional/api/test_merge_requests.py
@@ -181,11 +181,27 @@ def test_merge_request_reset_approvals(gitlab_url, project, wait_for_sidekiq):
     assert mr.reset_approvals()
 
 
+def test_cancel_merge_when_pipeline_succeeds(project, merge_request, wait_for_sidekiq):
+    mr = merge_request(source_branch="test_merge_request_merge", create_pipeline=True)
+    # Set to merge when the pipeline succeeds, which should never happen
+    mr.merge(merge_when_pipeline_succeeds=True)
+    wait_for_sidekiq(timeout=60)
+
+    mr = project.mergerequests.get(mr.iid)
+    assert mr.merged_at is None
+    assert mr.merge_when_pipeline_succeeds is True
+    cancel = mr.cancel_merge_when_pipeline_succeeds()
+    assert cancel == {"status": "success"}
+
+
 def test_merge_request_merge(project, merge_request, wait_for_sidekiq):
     mr = merge_request(source_branch="test_merge_request_merge")
     mr.merge()
     wait_for_sidekiq(timeout=60)
 
+    mr = project.mergerequests.get(mr.iid)
+    assert mr.merged_at is not None
+    assert mr.merge_when_pipeline_succeeds is False
     with pytest.raises(gitlab.GitlabMRClosedError):
         # Two merge attempts should raise GitlabMRClosedError
         mr.merge()
diff --git a/tests/functional/conftest.py b/tests/functional/conftest.py
index 3700ae6..b75a1e1 100644
--- a/tests/functional/conftest.py
+++ b/tests/functional/conftest.py
@@ -379,7 +379,7 @@ def merge_request(project, wait_for_sidekiq):
 
     to_delete = []
 
-    def _merge_request(*, source_branch: str):
+    def _merge_request(*, source_branch: str, create_pipeline: bool = False):
         # Wait for processes to be done before we start...
         # NOTE(jlvillal): Sometimes the CI would give a "500 Internal Server
         # Error". Hoping that waiting until all other processes are done will
@@ -401,6 +401,21 @@ def merge_request(project, wait_for_sidekiq):
                 "commit_message": "New commit in new branch",
             }
         )
+        if create_pipeline:
+            project.files.create(
+                {
+                    "file_path": ".gitlab-ci.yml",
+                    "branch": source_branch,
+                    "content": """
+test:
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+  script:
+    - sleep 24h  # We don't expect this to finish
+""",
+                    "commit_message": "Add a simple pipeline",
+                }
+            )
         mr = project.mergerequests.create(
             {
                 "source_branch": source_branch,