Add update-only configuration option (#92)

.gitignore

@@ -7,6 +7,7 @@ node_modules/
 
 # Editors
 .vscode
+.idea/**
 
 # Logs
 logs

README.md

@@ -82,6 +82,7 @@ jobs:
 | allow-repeats            | with     | Boolean flag to allow identical messages to be posted each time this action is run.                  | no       | false                              |
 | proxy-url                | with     | String for your proxy service URL if you'd like this to work with fork-based PRs.                    | no       |                                    |
 | issue                    | with     | Optional issue number override.                                                                      | no       |                                    |
+| update-only              | with     | Only update the comment if it already exists.                                                        | no       |                                    |
 | GITHUB_TOKEN             | env      | Valid GitHub token, can alternatively be defined in the env.                                         | no       |                                    |
 
 ## Advanced Uses
@@ -197,4 +198,4 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
 
 <!-- ALL-CONTRIBUTORS-LIST:END -->
 
-This project follows the [all-contributors](https://github.com/all-contributors/all-contributors) specification. Contributions of any kind welcome!
+This project follows the [all-contributors](https://github.com/all-contributors/all-contributors) specification. Contributions of any kind welcome!

__tests__/add-pr-comment.test.ts

@@ -24,6 +24,7 @@ type Inputs = {
   'message-failure'?: string
   'message-cancelled'?: string
   'message-skipped'?: string
+  'update-only'?: string
   status?: 'success' | 'failure' | 'cancelled' | 'skipped'
 }
 
@@ -175,6 +176,15 @@ describe('add-pr-comment action', () => {
     expect(core.setOutput).toHaveBeenCalledWith('comment-created', 'true')
   })
 
+  it('does not create a comment when updateOnly is true and no existing comment is found', async () => {
+    inputs.message = simpleMessage
+    inputs['allow-repeats'] = 'true'
+    inputs['update-only'] = 'true'
+
+    await expect(run()).resolves.not.toThrow()
+    expect(core.setOutput).toHaveBeenCalledWith('comment-created', 'false')
+  })
+
   it('creates a comment in another repo', async () => {
     inputs.message = simpleMessage
     inputs['repo-owner'] = 'my-owner'

action.yml

@@ -53,6 +53,9 @@ inputs:
   issue:
     description: "Override the message when a run is cancelled."
     required: false
+  update-only:
+    description: "Only update the comment if it already exists."
+    required: false
 outputs:
   comment-created:
     description: "Whether a comment was created."