Add option to use pull request title as commit message.

.github/workflows/automerge.yml

@@ -38,5 +38,6 @@ jobs:
       - uses: ./
         with:
           token: ${{ secrets.MY_GITHUB_TOKEN }}
+          squash-title: true
           do-not-merge-labels: never-merge
           pull-request: ${{ github.event.inputs.pull-request }}

README.md

@@ -21,6 +21,7 @@ Auto-merging is enabled for a branch given the following criteria:
 |------|-----------|-------------|
 | `token` | yes | A GitHub Token other than the default `GITHUB_TOKEN` needs to be specified in order to be able to trigger other workflows. |
 | `merge-method` | no | Specify which merge method to use. By default, will select the first one available in this order: `merge`, `squash`, `rebase` |
+| `squash-title` | no | Use the pull request title as the commit message when squashing. |
 | `do-not-merge-labels` | no | When any of the labels in this comma-separated list is applied to a pull request, it will not be merged automatically. |
 | `pull-request` | no | Try merging the specified pull request automatically. For example, you can pass an input from a `workflow_dispatch` event. |
 | `dry-run` | no | If set to `true`, will not actually merge pull requests but still perform all other checks. |

action.yml

@@ -18,6 +18,11 @@ inputs:
     description: >
       Specify which merge method to use. By default, will select the first one
       available in this order: `merge`, `squash`, `rebase`
+  squash-title:
+    required: false
+    description: >
+      Use the pull request title as the commit message when squashing.
+    default: false
   do-not-merge-labels:
     required: false
     description: >

src/automerge-action.ts

@@ -139,21 +139,29 @@ export class AutomergeAction {
 
         const mergeMethod = await this.determineMergeMethod()
 
-        try {
-          if (this.input.dryRun) {
-            core.info(`Would try merging pull request ${number}.`)
-          } else {
-            core.info(`Merging pull request ${number}:`)
+        const useTitle = this.input.squashTitle && mergeMethod === 'squash'
+        const commitTitle = useTitle ? `${pullRequest.title} (#${pullRequest.number})\n` : undefined
+        const commitMessage = useTitle ? '\n' : undefined
 
-            await this.octokit.pulls.merge({
-              ...github.context.repo,
-              pull_number: number,
-              sha: pullRequest.head.sha,
-              merge_method: mergeMethod,
-            })
+        const titleMessage = useTitle ? ` with title '${commitTitle}'` : undefined
 
-            core.info(`Successfully merged pull request ${number}.`)
-          }
+        if (this.input.dryRun) {
+          core.info(`Would try merging pull request ${number}${titleMessage}.`)
+          return false
+        }
+
+        try {
+          core.info(`Merging pull request ${number}${titleMessage}:`)
+          await this.octokit.pulls.merge({
+            ...github.context.repo,
+            pull_number: number,
+            sha: pullRequest.head.sha,
+            merge_method: mergeMethod,
+            commit_title: commitTitle,
+            commit_message: commitMessage,
+          })
+
+          core.info(`Successfully merged pull request ${number}.`)
 
           return false
         } catch (error) {

src/input.ts

@@ -21,6 +21,7 @@ function getNumber(input: string, options?: core.InputOptions): number | null {
 export class Input {
   token: string
   mergeMethod: MergeMethod
+  squashTitle: boolean
   doNotMergeLabels: string[]
   pullRequest: number | null
   dryRun: boolean
@@ -42,6 +43,7 @@ export class Input {
       }
     }
 
+    this.squashTitle = core.getInput('squash-title') === 'true'
     this.doNotMergeLabels = core.getInput('do-not-merge-labels').split(',')
     this.pullRequest = getNumber('pull-request')
     this.dryRun = core.getInput('dry-run') === 'true'