Use pagination to find all files

[ruudk]

Fixes #19

This increases the page size from the default 30 to the maximum of 100.

It then uses octokit.paginate to automatically fetch all pages.

No idea if this works. Let's see what the tests do.

[ruudk]

Ok, I just tried this branch out and it solves my problem 🎉

I couldn't get the mocked test to pass, @gkampitakis could you help out? 🙏

[gkampitakis]

Updated test

```ts
import { getFiles } from '../src/pr-files';
import { Octokit } from '../src/types';

const sleep = (time: number) =>
  new Promise(resolve => setTimeout(resolve, time));
const execSpy = jest.fn();
const diffCMD = 'git diff origin/master...origin/pr -- src/data.ts';

jest.mock('util', () => {
  const original = jest.requireActual('util');

  return {
    ...original,
    promisify: () => async (command: string) => {
      await sleep(2000);
      execSpy(command);
      return { stdout: 'mock-diff', stderr: '' };
    }
  };
});

const spy = jest.fn();
const mockOctokit = {
  rest: {
    pulls: {
      listFiles: "mock"
    }
  },
  paginate: (mock: string, args: any) => {
    spy(mock)
    spy(args)
    return [
      {
        status: 'added',
        filename: 'src/data.ts',
        additions: 10
      },
      {
        status: 'added',
        filename: 'data.js',
        additions: 4,
        patch: 'mock-patch'
      },
      {
        status: 'removed',
        filename: 'mock-file.spec.ts',
        additions: 4,
        patch: 'mock-patch'
      },
      {
        status: 'unchanged',
        filename: 'more-data.ts',
        additions: 4,
        patch: 'mock-patch'
      },
      {
        status: 'modified',
        filename: 'lib/index.js',
        additions: 0,
        patch: 'mock-patch'
      },
      {
        status: 'modified',
        filename: 'index.ts',
        additions: 2,
        patch: 'mock-patch'
      }
    ]
  },
} as unknown as Octokit;
const owner = 'mock-owner';
const repo = 'mock-repo';
const prNumber = 10;
const base = 'master';
const head = 'pr';

describe('getFiles', () => {
  beforeEach(() => {
    spy.mockClear();
  });

  it('should return correct files', async () => {
    const files = await getFiles({
      octokit: mockOctokit,
      owner,
      repo,
      base,
      head,
      prNumber
    });

    expect(files).toEqual([
      { filename: 'src/data.ts', patch: 'mock-diff' },
      { filename: 'data.js', patch: 'mock-patch' },
      { filename: 'index.ts', patch: 'mock-patch' }
    ]);
    expect(spy).toHaveBeenCalledWith("mock")
    expect(spy).toHaveBeenCalledWith({
      owner,
      repo,
      pull_number: prNumber,
      per_page: 100,
      mediaType: {
        format: 'diff'
      }
    });
    expect(execSpy).toHaveBeenNthCalledWith(1, diffCMD);
  });

  it('should filter out matching files', async () => {
    const files = await getFiles({
      octokit: mockOctokit,
      owner,
      repo,
      prNumber,
      head,
      base,
      ignoreFilesPattern: '.js$'
    });

    expect(files).toEqual([
      { filename: 'src/data.ts', patch: 'mock-diff' },
      { filename: 'index.ts', patch: 'mock-patch' }
    ]);
    expect(spy).toHaveBeenCalledWith({
      owner,
      repo,
      pull_number: prNumber,
      per_page: 100,
      mediaType: {
        format: 'diff'
      }
    });
    expect(execSpy).toHaveBeenNthCalledWith(1, diffCMD);
  });
});

Does the paginate return only the array of objects now?