feat: add support for pull_request events (#13)

index.js

@@ -6,34 +6,58 @@ const run = async () => {
   const prTitle = core.getInput('pr_title');
   const prBody = core.getInput('pr_body');
   const baseBranch = core.getInput('destination_branch');
-  const sourceBranch = github.context.ref.replace(/^refs\/heads\//, '');
+  // On 'push' events, github.context.ref is in format 'refs/heads/<sourceBranch>'
+  // On 'pull_request' events, github.contest.ref is in format 'refs/pull/<pullRequestNumber>/merge'
+  // See https://docs.github.com/en/actions/learn-github-actions/environment-variables
+  let sourceBranch = github.context.ref.match(/^refs\/heads\/(.?)$/)?.[1];
+  const sourcePullRequestNumber = github.context.ref.match(/^refs\/pull\/(\d+)\/merge/)?.[1];
 
   const credentials = {
     owner: github.context.repo.owner,
     repo: github.context.repo.repo,
   };
 
   const octokit = github.getOctokit(githubToken);
-  core.info(`Looking up a pull request with a source branch "${sourceBranch || '<not found>'}" and a base branch "${baseBranch || '<not specified>'}"`);
 
-  const branchHead = `${credentials.owner}:${sourceBranch}`;
-  const { data: pulls } = await octokit.rest.pulls.list({
-    ...credentials,
-    base: baseBranch,
-    head: branchHead,
-  });
+  let pullRequest;
+  if (sourceBranch) { // 'push' event
+    core.info(`Looking up a pull request with a source branch "${sourceBranch || '<not found>'}" and a base branch "${baseBranch || '<not specified>'}"`);
 
-  if (pulls.length === 0) {
-    throw new Error(`No pull request found for a source branch "${sourceBranch || '<not found>'}" and a base branch "${baseBranch || '<not specified>'}"`);
-  }
+    const branchHead = `${credentials.owner}:${sourceBranch}`;
+    const { data: pulls } = await octokit.rest.pulls.list({
+      ...credentials,
+      base: baseBranch,
+      head: branchHead,
+    });
+
+    if (pulls.length === 0) {
+      throw new Error(`No pull request found for a source branch "${sourceBranch || '<not found>'}" and a base branch "${baseBranch || '<not specified>'}"`);
+    }
+
+    pullRequest = pulls.find((p) => p.state === 'open');
+    if (pullRequest == null) {
+      throw new Error(`No open pull requests found for a source branch "${sourceBranch || '<not found>'}" and a base branch "${baseBranch || '<not specified>'}"`);
+    }
+  } else { // 'pull_request' event
+    core.info(`Looking up a pull request #${sourcePullRequestNumber}`);
+
+    ({ data: pullRequest } = await octokit.rest.pulls.get({
+      ...credentials,
+      pull_number: sourcePullRequestNumber,
+    }));
+
+    if (pullRequest == null) {
+      throw new Error(`Pull request #${sourcePullRequestNumber} was not found`);
+    }
+    if (pullRequest.state !== 'open') {
+      throw new Error(`Pull request #${sourcePullRequestNumber} is not open`);
+    }
 
-  const pullRequest = pulls.find((p) => p.state === 'open');
-  if (pullRequest == null) {
-    throw new Error(`No open pull requests found for a source branch "${sourceBranch || '<not found>'}" and a base branch "${baseBranch || '<not specified>'}"`);
+    sourceBranch = pullRequest.head.ref;
   }
 
   const { number: pullNumber, base: { ref: pullRequestTargetBranch } } = pullRequest;
-  core.info(`Pull request #${pullNumber} has been found for  a source branch "${sourceBranch || '<not found>'}" and a base branch "${baseBranch || '<not specified>'}"`);
+  core.info(`Pull request #${pullNumber} has been found for a source branch "${sourceBranch || '<not found>'}" and a base branch "${baseBranch || '<not specified>'}"`);
 
   const params = {
     ...credentials,

package.json

@@ -1,6 +1,6 @@
 {
   "name": "update-pull-request-description-on-push",
-  "version": "2.0.0",
+  "version": "2.1.0",
   "description": "Update pull request description on push",
   "main": "index.js",
   "scripts": {