Merge pull request #10074 from cli/kw/cli-7011-fix-delete-branch-with-merge-queue-v2

`gh pr merge --delete-branch` exits with error when merge requested via merge queue

pkg/cmd/pr/merge/merge.go

@@ -241,7 +241,14 @@ func (m *mergeContext) warnIfDiverged() {
 // Check if the current state of the pull request allows for merging
 func (m *mergeContext) canMerge() error {
 	if m.mergeQueueRequired {
-		// a pull request can always be added to the merge queue
+		// Requesting branch deletion on a PR with a merge queue
+		// policy is not allowed. Doing so can unexpectedly
+		// delete branches before merging, close the PR, and remove
+		// the PR from the merge queue.
+		if m.opts.DeleteBranch {
+			return fmt.Errorf("%s Cannot use `-d` or `--delete-branch` when merge queue enabled", m.cs.FailureIcon())
+		}
+		// Otherwise, a pull request can always be added to the merge queue
 		return nil
 	}
 

pkg/cmd/pr/merge/merge_test.go

@@ -659,6 +659,29 @@ func TestPrMerge_deleteBranch(t *testing.T) {
 	`), output.Stderr())
 }
 
+func TestPrMerge_deleteBranch_mergeQueue(t *testing.T) {
+	http := initFakeHTTP()
+	defer http.Verify(t)
+
+	shared.RunCommandFinder(
+		"",
+		&api.PullRequest{
+			ID:                  "PR_10",
+			Number:              10,
+			State:               "OPEN",
+			Title:               "Blueberries are a good fruit",
+			HeadRefName:         "blueberries",
+			BaseRefName:         "main",
+			MergeStateStatus:    "CLEAN",
+			IsMergeQueueEnabled: true,
+		},
+		baseRepo("OWNER", "REPO", "main"),
+	)
+
+	_, err := runCommand(http, nil, "blueberries", true, `pr merge --merge --delete-branch`)
+	assert.Contains(t, err.Error(), "X Cannot use `-d` or `--delete-branch` when merge queue enabled")
+}
+
 func TestPrMerge_deleteBranch_nonDefault(t *testing.T) {
 	http := initFakeHTTP()
 	defer http.Verify(t)