Handle error after rebase (#11)

Author: pepakriz

src/GitlabApi.ts

@@ -75,6 +75,7 @@ export interface MergeRequestInfo extends MergeRequest {
 	pipeline: MergeRequestPipeline | null;
 	diverged_commits_count: number;
 	rebase_in_progress: boolean;
+	merge_error: string | null;
 }
 
 export interface DiscussionNote {

src/MergeRequestAcceptor.ts

@@ -16,6 +16,7 @@ export enum AcceptMergeRequestResultKind {
 	ClosedMergeRequest,
 	ReassignedMergeRequest,
 	CanNotBeMerged,
+	RebaseFailed,
 	FailedPipeline,
 	Unauthorized,
 }
@@ -51,10 +52,16 @@ interface UnauthorizedResponse {
 	mergeRequestInfo: MergeRequestInfo;
 }
 
+interface RebaseFailedResponse {
+	kind: AcceptMergeRequestResultKind.RebaseFailed;
+	mergeRequestInfo: MergeRequestInfo;
+}
+
 type AcceptMergeRequestResult = SuccessResponse
 	| ClosedMergeRequestResponse
 	| ReassignedMergeRequestResponse
 	| CanNotBeMergedResponse
+	| RebaseFailedResponse
 	| FailedPipelineResponse
 	| UnauthorizedResponse;
 
@@ -109,9 +116,9 @@ export const acceptMergeRequest = async (gitlabApi: GitlabApi, mergeRequest: Mer
 			throw new Error(`Unexpected MR status: ${mergeRequestInfo.state}`);
 		}
 
-		if (mergeRequestInfo.merge_status !== MergeStatus.CanBeMerged || mergeRequestInfo.work_in_progress) {
+		if (mergeRequestInfo.merge_error !== null) {
 			return {
-				kind: AcceptMergeRequestResultKind.CanNotBeMerged,
+				kind: AcceptMergeRequestResultKind.RebaseFailed,
 				mergeRequestInfo,
 			};
 		}
@@ -122,6 +129,13 @@ export const acceptMergeRequest = async (gitlabApi: GitlabApi, mergeRequest: Mer
 			continue;
 		}
 
+		if (mergeRequestInfo.merge_status !== MergeStatus.CanBeMerged || mergeRequestInfo.work_in_progress) {
+			return {
+				kind: AcceptMergeRequestResultKind.CanNotBeMerged,
+				mergeRequestInfo,
+			};
+		}
+
 		if (mergeRequestInfo.diverged_commits_count > 0) {
 			await gitlabApi.updateMergeRequest(mergeRequest.project_id, mergeRequest.iid, {
 				labels: [...filterBotLabels(mergeRequestInfo.labels), BotLabels.Rebasing].join(','),

src/index.ts

@@ -110,6 +110,17 @@ const runMergeRequestCheckerLoop = async (user: User) => {
 				return;
 			}
 
+			if (result.kind === AcceptMergeRequestResultKind.RebaseFailed) {
+				console.log(`[MR] rebase failed: ${result.mergeRequestInfo.merge_error}, assigning back`);
+
+				await Promise.all([
+					assignToAuthorAndResetLabels(gitlabApi, result.mergeRequestInfo),
+					sendNote(gitlabApi, mergeRequest, `Merge request can't be merged: ${result.mergeRequestInfo.merge_error}`),
+				]);
+
+				return;
+			}
+
 			if (result.kind === AcceptMergeRequestResultKind.ClosedMergeRequest) {
 				console.log(`[MR] Merge request is closed, ending`);