feat(config): support reading from local file if it exists

[lrstanley]

Currently, actions/labeler can only read the configuration from the source repository, due to it using the context and API to fetch the configuration file. This PR adds support for first checking to see if a file matching the provided path exists locally, before it makes a call to the API to get the file.

The primary benefit for this, is it works well with reusable workflows, as all you have to do is grab the file from a central location, before running this on the target repository.

• closes Add ability to apply shared configs from another repo #141 (this PR is a simpler solution that allows for the same functionality)
• closes Issue when share workflow within organization #123

[mac2000]

This change will also fix #16

comment with back link

[javiergonzalezGenially]

Any news about this? This is actually needed when labeler.yml is auto-generated in build time.

[simbo]

@lrstanley I created a PR for your PR, that updates the branch and uses async readFile.
https://github.com/lrstanley/labeler/pull/1

[AndreiLobanovich]

Hello, @lrstanley!
Thanks for your contribution!
I left a few comments, otherwise your solution looks great.

[AndreiLobanovich]

Hey, @lrstanley! Thanks for your changes. Could you also provide us with the test case for this functionality?

[AndreiLobanovich]

Hey, @lrstanley!
Do you have some spare time to finish this PR? Is there anything I can help you with?

[lrstanley]

Hey, @lrstanley! Thanks for your changes. Could you also provide us with the test case for this functionality?

I don't see any existing mock/testing functionality for the actual reads from the API, and if I write a test, it should probably cover the case if a file doesn't exist (or similar), which means it'd try and read from the remote. Not sure best practice on how to implement that. Do the octokit libraries provide ways of mocking those calls?

[AndreiLobanovich]

@lrstanley as for tests - you may utilize the following approach.

[MaksimZhukov]

I don't see any existing mock/testing functionality for the actual reads from the API, and if I write a test, it should probably cover the case if a file doesn't exist (or similar), which means it'd try and read from the remote. Not sure best practice on how to implement that. Do the octokit libraries provide ways of mocking those calls?

I think we can add two tests here:

1. uses local configuration file if it exists
2. fetches the content of configuration file via API if not found locally

Here is an example of the first test case:

  it('uses local configuration file if it exists', async () => {
    const configFile = 'only_pdfs.yml';
    const configFilePath = path.join(__dirname, 'fixtures', configFile);
    
    configureInput({
      'configuration-path': configFilePath
    });

    await run();

    expect(reposMock).toHaveBeenCalledTimes(0);
  });

[MaksimZhukov]

@lrstanley thank you for the contribution!