Fix #205: Fails CI when a don't merge label get added on a pull reque…

…st. (#264)

actions/src/dispatcher.js

@@ -21,6 +21,7 @@ const { context } = require('@actions/github');
 const issueLabelsModule = require('./issues/checkIssueLabels');
 const claCheckGithubActionModule = require('./pull_requests/claCheck');
 const constants = require('../../constants');
+const PRLabelsModule = require('./pull_requests/labelCheck');
 
 module.exports = {
   async dispatch(event, action) {
@@ -42,6 +43,12 @@ module.exports = {
               core.info('cla check triggered');
               await claCheckGithubActionModule.claCheckGithubAction();
               break;
+            case constants.prLabelCheck:
+              await PRLabelsModule.checkLabels();
+              break;
+            case constants.dontMergeLabelCheck:
+              await PRLabelsModule.checkUnLabeled();
+              break;
           }
         }
       }

actions/src/pull_requests/labelCheck.js

@@ -0,0 +1,84 @@
+// Copyright 2021 The Oppia Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS-IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/**
+ * @fileoverview File to handle checks when a pull request is labeled.
+ */
+
+const core = require('@actions/core');
+const { context, GitHub } = require('@actions/github');
+const DONT_MERGE_LABEL_PREFIX = "PR: don't merge";
+
+const checkLabels = async () => {
+  core.info('Checking newly added label...');
+  const token = core.getInput('repo-token');
+  const label = context.payload.label;
+  const octokit = new GitHub(token);
+
+  if (label.name.startsWith(DONT_MERGE_LABEL_PREFIX)) {
+    await handleDontMergeLabel(octokit, label.name);
+  }
+};
+
+/**
+ * Handles cases when a good first issue gets added by a non whitelisted user.
+ *
+ * @param {import('@actions/github').GitHub} octokit
+ */
+const handleDontMergeLabel = async (octokit, label) => {
+  core.setFailed(
+    'This PR should not be merged because it has a ' + label + ' label.'
+  );
+};
+
+/**
+ * Handles cases when a good first issue gets added by a non whitelisted user.
+ *
+ * @param {import('@actions/github').GitHub} octokit
+ */
+const handleDontMergeLabelRemoved = async(octokit) => {
+  const {data: pullRequest} = await octokit.pulls.get({
+    pull_number: context.payload.pull_request.number,
+    owner: context.payload.repository.owner.login,
+    repo: context.payload.repository.name,
+  });
+
+  const labelNames = pullRequest.labels.map(label => label.name);
+
+  const dontMergeLabel = labelNames.find(
+    label => label.startsWith(DONT_MERGE_LABEL_PREFIX)
+  );
+
+  if (dontMergeLabel) {
+    await handleDontMergeLabel(octokit, dontMergeLabel);
+  } else {
+    core.info("This PR does not contain a PR don't merge label");
+  }
+};
+
+const checkUnLabeled = async () => {
+  core.info('Checking newly removed label...');
+  const token = core.getInput('repo-token');
+  const label = context.payload.label;
+  const octokit = new GitHub(token);
+
+  if (label.name.startsWith(DONT_MERGE_LABEL_PREFIX)) {
+    await handleDontMergeLabelRemoved(octokit, label.name);
+  }
+};
+
+module.exports = {
+  checkLabels,
+  checkUnLabeled,
+};