dangerfile.ts

import { danger, warn, fail, message, TextDiff } from 'danger';

const SMALL_PR_FILES = 10;
const SMALL_PR_LINES = 200;

const DOC_FILE_MATCH = '**/*.md';
const SRC_FILE_REGEXP = /test.*\.([tj]s?)$/;

// No PR is too small to include a description of why you made a change
if (!danger.github.pr.body || !danger.github.pr.body.includes('## What\'s this PR do?')) {
  const title = ':clipboard: Missing Summary';
  const idea =
    'Can you add a Summary? ' +
    'To do so, add a `## What\'s this PR do?` section to your PR description. ' +
    'This is a good place to explain the motivation for making this change.';
  message(`${title} - <i>${idea}</i>`);
}

if (!danger.github.pr.title) {
  const title = ':id: Missing PR Title';
  const idea = 'Can you add the relevant title?';
  warn(`${title} - <i>${idea}</i>`);
}

const touchedFiles = danger.git.created_files.concat(danger.git.modified_files);
const allFiles = touchedFiles.concat(danger.git.deleted_files);

const diffsList: Promise<(TextDiff | null)[]> = Promise.all(allFiles.map((p) => danger.git.diffForFile(p)));

diffsList
  .then((diffs) => diffs.filter(Boolean) as TextDiff[])
  .then((diffs) => ({
    removed: diffs.reduce((lines, diff) => lines + diff.removed.split('\n').length, 0),
    added: diffs.reduce((lines, diff) => lines + diff.added.split('\n').length, 0),
    lines: diffs.reduce((lines, diff) => lines + diff.added.split('\n').length + diff.removed.split('\n').length, 0),
    files: diffs.length,
  }))
  .then((diff) => {
    if (diff.added < diff.removed) {
      message('Thanks! We :heart: removing more lines than added!');
    }

    if (diff.lines <= SMALL_PR_LINES && diff.files <= SMALL_PR_FILES) {
      message('Thanks! We :heart: small PRs!');
    }

    if (diff.lines > SMALL_PR_LINES) {
      warn(`This PR is changing more than ${SMALL_PR_LINES} lines.`);
    }

    if (diff.files > SMALL_PR_FILES) {
      warn(`This PR is changing more than ${SMALL_PR_FILES} files.`);
    }
  });

// Request changes to src also include changes to tests.
const docs = danger.git.fileMatch(DOC_FILE_MATCH);
const appModified = touchedFiles.some((p) => p.match(SRC_FILE_REGEXP));

if (docs.edited) {
  message('Thanks for updating docs! We :heart: documentation!');
}

if (appModified) {
  message('Thanks for updating tests! Only YOU can prevent production fires. :fire::evergreen_tree::bear:');
}

// Warns if there are changes to package.json, and tags the team.
const packageJSON = danger.git.fileMatch('package.json');
const yarnLockfile = danger.git.fileMatch('yarn.lock');
const npmLockfile = danger.git.fileMatch('package-lock.json');

if (packageJSON.modified) {
  const title = ':lock: package.json';
  const idea = 'Changes were made to package.json.';
  warn(`${title} - <i>${idea}</i>`);
}

if (packageJSON.modified && !yarnLockfile.modified) {
  const title = ':lock: package.json';
  const idea =
    'If you’ve changed any dependencies (added, removed or updated any packages), ' +
    'please run `yarn` and commit changes in yarn.lock file. ' +
    'Make sure you’re using the correct yarn and node versions.';
  fail(`${title} - <i>${idea}</i>`);
}

if (!packageJSON.modified && yarnLockfile.modified) {
  const title = ':lock: package.json';
  const idea =
    'Changes were made to `yarn.lock`, but not to `package.json`. ' +
    'Please remove `yarn.lock` changes from your pull request. ' +
    'Try to run `git checkout master -- yarn.lock` and commit changes.';
  fail(`${title} - <i>${idea}</i>`);
}

if (npmLockfile.modified) {
  const title = ':rage: package-lock.json';
  const idea =
    'This PR is adding file `package-lock.json` and we don\'t use npm!. ' +
    'Please remove `package-lock.json` and commit changes.';
  fail(`${title} - <i>${idea}</i>`);
}