Provide "pending" mergeability state, wherein updates are polled, fixes #1412

Author: Jackson Kearl

preview-src/cache.ts

@@ -4,7 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { vscode } from './message';
-import { PullRequestStateEnum, IAccount, ReviewState, ILabel, MergeMethod, MergeMethodsAvailability } from '../src/github/interface';
+import { PullRequestStateEnum, IAccount, ReviewState, ILabel, MergeMethod, MergeMethodsAvailability, PullRequestMergeability } from '../src/github/interface';
 import { TimelineEvent } from '../src/common/timelineEvent';
 import { ReposGetCombinedStatusForRefResponse } from '@octokit/rest';
 
@@ -33,7 +33,7 @@ export interface PullRequest {
 	pendingCommentText?: string;
 	pendingCommentDrafts?: { [key: string]: string; };
 	status: ReposGetCombinedStatusForRefResponse;
-	mergeable: boolean;
+	mergeable: PullRequestMergeability;
 	defaultMergeMethod: MergeMethod;
 	mergeMethodsAvailability: MergeMethodsAvailability;
 	supportsGraphQl: boolean;

preview-src/context.tsx

@@ -35,6 +35,9 @@ export class PRContext {
 	public refresh = () =>
 		this.postMessage({ command: 'pr.refresh' })
 
+	public checkMergeability = () =>
+		this.postMessage({ command: 'pr.checkMergeability' })
+
 	public merge = (args: { title: string, description: string, method: MergeMethod }) =>
 		this.postMessage({ command: 'pr.merge', args	})
 

preview-src/merge.tsx

@@ -2,14 +2,14 @@ import * as React from 'react';
 import { PullRequest } from './cache';
 import PullRequestContext from './context';
 import { useContext, useReducer, useRef, useState, useEffect, useCallback } from 'react';
-import { PullRequestStateEnum, MergeMethod } from '../src/github/interface';
+import { PullRequestStateEnum, MergeMethod, PullRequestMergeability } from '../src/github/interface';
 import { checkIcon, deleteIcon, pendingIcon, alertIcon } from './icon';
 import { Avatar, } from './user';
 import { nbsp } from './space';
 import { groupBy } from '../src/common/utils';
 
 export const StatusChecks = (pr: PullRequest) => {
-	const { state, status, mergeable } = pr;
+	const { state, status, mergeable: _mergeable } = pr;
 	const [showDetails, toggleDetails] = useReducer(
 		show => !show,
 		status.statuses.some(s => s.state === 'failure')) as [boolean, () => void];
@@ -22,6 +22,18 @@ export const StatusChecks = (pr: PullRequest) => {
 		}
 	}, status.statuses);
 
+	const [mergeable, setMergeability] = useState(_mergeable);
+	const { checkMergeability } = useContext(PullRequestContext);
+
+	useEffect(() => {
+		const handle = setInterval(async () => {
+			if (mergeable === PullRequestMergeability.Unknown) {
+				setMergeability(await checkMergeability());
+			}
+		}, 3000);
+		return () => clearInterval(handle);
+	});
+
 	return <div id='status-checks'>{
 		state === PullRequestStateEnum.Merged
 			?
@@ -56,22 +68,26 @@ export const StatusChecks = (pr: PullRequest) => {
 					: null
 				}
 				<MergeStatus mergeable={mergeable} />
-				<PrActions {...pr} />
+				<PrActions {...{...pr, mergeable}} />
 			</>
 	}</div>;
 };
 
 export default StatusChecks;
 
-export const MergeStatus = ({ mergeable }: Pick<PullRequest, 'mergeable'>) =>
-	<div className='status-item status-section'>
-		{mergeable ? checkIcon : deleteIcon}
+export const MergeStatus = ({ mergeable }: Pick<PullRequest, 'mergeable'>) => {
+	return <div className='status-item status-section'>
+		{mergeable === PullRequestMergeability.Mergeable ? checkIcon :
+			mergeable === PullRequestMergeability.NotMergeable ? deleteIcon : pendingIcon}
 		<div>{
-			mergeable
+			mergeable === PullRequestMergeability.Mergeable
 				? 'This branch has no conflicts with the base branch'
-				: 'This branch has conflicts that must be resolved'
+				: mergeable === PullRequestMergeability.NotMergeable
+					? 'This branch has conflicts that must be resolved'
+					: 'Checking if this branch can be merged...'
 		}</div>
 	</div>;
+};
 
 export const ReadyForReview = () => {
 	const [isBusy, setBusy] = useState(false);
@@ -120,7 +136,7 @@ export const PrActions = (pr: PullRequest) => {
 		? hasWritePermission || canEdit
 			? <ReadyForReview/>
 			: null
-		: mergeable && hasWritePermission
+		: mergeable === PullRequestMergeability.Mergeable && hasWritePermission
 			? <Merge {...pr} />
 			: null;
 };

preview-src/test/builder/pullRequest.ts

@@ -1,6 +1,6 @@
 import { createBuilderClass } from '../../../src/test/builders/base';
 import { PullRequest } from '../../cache';
-import { PullRequestStateEnum } from '../../../src/github/interface';
+import { PullRequestStateEnum, PullRequestMergeability } from '../../../src/github/interface';
 import { CombinedStatusBuilder } from '../../../src/test/builders/rest/combinedStatusBuilder';
 
 import { AccountBuilder } from './account';
@@ -26,7 +26,7 @@ export const PullRequestBuilder = createBuilderClass<PullRequest>()({
 	pendingCommentText: {default: null},
 	pendingCommentDrafts: {default: null},
 	status: {linked: CombinedStatusBuilder},
-	mergeable: {default: true},
+	mergeable: {default: PullRequestMergeability.Mergeable},
 	defaultMergeMethod: {default: 'merge'},
 	mergeMethodsAvailability: {default: {merge: true, squash: true, rebase: true}},
 	supportsGraphQl: {default: true},

resources/icons/dot.svg

@@ -258,6 +258,20 @@ query PullRequest($owner: String!, $name: String!, $number: Int!) {
 	}
 }
 
+query PullRequestMergeability($owner: String!, $name: String!, $number: Int!) {
+	repository(owner: $owner, name: $name) {
+		pullRequest(number: $number) {
+			mergeable
+		}
+	}
+	rateLimit {
+		limit
+		cost
+		remaining
+		resetAt
+	}
+}
+
 query PullRequestState($owner: String!, $name: String!, $number: Int!) {
 	repository(owner: $owner, name: $name) {
 		pullRequest(number: $number) {

src/github/enterprise.gql

@@ -7,13 +7,13 @@ import * as vscode from 'vscode';
 import Octokit = require('@octokit/rest');
 import Logger from '../common/logger';
 import { Remote, parseRemote } from '../common/remote';
-import { IAccount, RepoAccessAndMergeMethods } from './interface';
+import { IAccount, RepoAccessAndMergeMethods, PullRequestMergeability } from './interface';
 import { PullRequestModel } from './pullRequestModel';
 import { CredentialStore, GitHub } from './credentials';
 import { AuthenticationError } from '../common/authentication';
 import { QueryOptions, MutationOptions, ApolloQueryResult, NetworkStatus, FetchResult } from 'apollo-boost';
 import { PRCommentController } from '../view/prCommentController';
-import { convertRESTPullRequestToRawPullRequest, parseGraphQLPullRequest } from './utils';
+import { convertRESTPullRequestToRawPullRequest, parseGraphQLPullRequest, parseMergeability } from './utils';
 import { PullRequestResponse, MentionableUsersResponse } from './graphql';
 
 export const PULL_REQUEST_PAGE_SIZE = 20;
@@ -356,6 +356,31 @@ export class GitHubRepository implements vscode.Disposable {
 		}
 	}
 
+	async getPullRequestMergeability(id: number): Promise<PullRequestMergeability> {
+		try {
+			Logger.debug(`Fetch pull request mergeability ${id} - enter`, GitHubRepository.ID);
+			const { supportsGraphQl, query, remote, schema } = await this.ensure();
+
+			if (supportsGraphQl) {
+				const { data } = await query<PullRequestResponse>({
+					query: schema.PullRequestMergeability,
+					variables: {
+						owner: remote.owner,
+						name: remote.repositoryName,
+						number: id
+					}
+				});
+				Logger.debug(`Fetch pull request mergeability ${id} - done`, GitHubRepository.ID);
+				return parseMergeability(data.repository.pullRequest.mergeable);
+			} else {
+				throw Error('GitHub repos without v4 API support (GraphQL) are no longer supported.');
+			}
+		} catch (e) {
+			Logger.appendLine(`GithubRepository> Unable to fetch PR Mergeability: ${e}`);
+			return PullRequestMergeability.Unknown;
+		}
+	}
+
 	async deleteBranch(pullRequestModel: PullRequestModel): Promise<void> {
 		const { octokit } = await this.ensure();
 

src/github/githubRepository.ts

@@ -21,6 +21,12 @@ export enum PullRequestStateEnum {
 	Closed,
 }
 
+export enum PullRequestMergeability {
+	Mergeable,
+	NotMergeable,
+	Unknown
+}
+
 export interface ReviewState {
 	reviewer: IAccount;
 	state: string;
@@ -72,7 +78,7 @@ export interface PullRequest {
 	user: IAccount;
 	labels: ILabel[];
 	merged: boolean;
-	mergeable?: boolean;
+	mergeable: PullRequestMergeability;
 	isDraft?: boolean;
 }
 

src/github/interface.ts

@@ -11,7 +11,7 @@ import { IComment } from '../common/comment';
 import { Remote, parseRepositoryRemotes } from '../common/remote';
 import { TimelineEvent, EventType, ReviewEvent as CommonReviewEvent, isReviewEvent, isCommitEvent } from '../common/timelineEvent';
 import { GitHubRepository, PullRequestData } from './githubRepository';
-import { IPullRequestsPagingOptions, PRType, ReviewEvent, IPullRequestEditData, PullRequest, IRawFileChange, IAccount, ILabel, RepoAccessAndMergeMethods } from './interface';
+import { IPullRequestsPagingOptions, PRType, ReviewEvent, IPullRequestEditData, PullRequest, IRawFileChange, IAccount, ILabel, RepoAccessAndMergeMethods, PullRequestMergeability } from './interface';
 import { PullRequestGitHelper, PullRequestMetadata } from './pullRequestGitHelper';
 import { PullRequestModel, IResolvedPullRequestModel } from './pullRequestModel';
 import { GitHubManager } from '../authentication/githubServer';
@@ -1922,6 +1922,19 @@ export class PullRequestManager implements vscode.Disposable {
 		return pr;
 	}
 
+	async resolvePullRequestMergeability(owner: string, repositoryName: string, pullRequestNumber: number): Promise<PullRequestMergeability> {
+		const githubRepo = this._githubRepositories.find(repo =>
+			repo.remote.owner.toLowerCase() === owner.toLowerCase() && repo.remote.repositoryName.toLowerCase() === repositoryName.toLowerCase()
+		);
+
+		if (!githubRepo) {
+			return PullRequestMergeability.Unknown;
+		}
+
+		return githubRepo.getPullRequestMergeability(pullRequestNumber);
+
+	}
+
 	async getMatchingPullRequestMetadataForBranch() {
 		if (!this.repository || !this.repository.state.HEAD || !this.repository.state.HEAD.name) {
 			return null;

src/github/pullRequestManager.ts

@@ -7,7 +7,7 @@
 import * as path from 'path';
 import * as vscode from 'vscode';
 import Octokit = require('@octokit/rest');
-import { PullRequestStateEnum, ReviewEvent, ReviewState, ILabel, IAccount, MergeMethodsAvailability, MergeMethod } from './interface';
+import { PullRequestStateEnum, ReviewEvent, ReviewState, ILabel, IAccount, MergeMethodsAvailability, MergeMethod, PullRequestMergeability } from './interface';
 import { onDidUpdatePR } from '../commands';
 import { formatError } from '../common/utils';
 import { GitErrorCodes } from '../api/api';
@@ -124,6 +124,14 @@ export class PullRequestOverviewPanel {
 		}, null, this._disposables);
 	}
 
+	private async checkMergeability(): Promise<PullRequestMergeability> {
+		return this._pullRequestManager.resolvePullRequestMergeability(
+			this._pullRequest.remote.owner,
+			this._pullRequest.remote.repositoryName,
+			this._pullRequest.prNumber
+		);
+	}
+
 	public async refreshPanel(): Promise<void> {
 		if (this._panel && this._panel.visible) {
 			this.update(this._pullRequest, this._descriptionNode);
@@ -324,6 +332,8 @@ export class PullRequestOverviewPanel {
 				return this.openDiff(message);
 			case 'pr.edit-title':
 				return this.editTitle(message);
+			case 'pr.checkMergeability':
+				return this._replyMessage(message, await this.checkMergeability());
 			case 'pr.refresh':
 				this.refreshPanel();
 				return;