Danger File for PR checks

dangerfile.js

const { danger, warn, fail } = require('danger');
const { uniq } = require('lodash');
const fs = require('fs');
const path = require('path');

// Setup
const pr = danger.github.pr;
const bodyAndTitle = (pr.body + pr.title).toLowerCase();

// Custom modifiers for people submitting PRs to be able to say "skip this"
const skipTests = bodyAndTitle.includes('skip new tests');
const skipVisualDiff = bodyAndTitle.includes('skip visual diff');
const skipStories = bodyAndTitle.includes('skip stories');
const hasScreenShots =
  pr.body.includes('.png') ||
  pr.body.includes('.jpg') ||
  pr.body.includes('.gif');

// Check for description
if (danger.github.pr.body.length < 10) {
  fail('This pull request needs a description.');
}

// Check for reference to JIRA issue
const JIRA_REGEX = /(DAR-|MLSSERV-)/;
if (!JIRA_REGEX.test(bodyAndTitle)) {
  warn(
    'Is this PR related to a Jira issue? If so link it via the PR title or description by adding the issue id (DAR-XXX)'
  );
}

// Warn when there is a big PR
const bigPRThreshold = 2000;
if (pr.additions + pr.deletions > bigPRThreshold) {
  warn(':exclamation: Big PR');
}

// Gather changes
const modifiedFiles = danger.git.modified_files.filter(path =>
  path.endsWith('js')
);

// Check for console.log statements
modifiedFiles.forEach(file => {
  const content = fs.readFileSync(file).toString();
  if (content.includes('console.log') || content.includes('console.warn')) {
    fail(`a \`console.log\` was left in file (${file})`);
  }
});

// Check that every file touched has a corresponding test file
const correspondingTestsForModifiedFiles = modifiedFiles.map(f => {
  const newPath = path.dirname(f);
  const name = path.basename(f);
  return `${newPath}/__tests__/${name}`;
});

const testFilesThatDontExist = correspondingTestsForModifiedFiles
  .filter(f => !f.includes('__stories__')) // skip stories
  .filter(f => !fs.existsSync(f));

if (testFilesThatDontExist.length > 0 && !skipTests) {
  const output = `Missing Test Files:
${testFilesThatDontExist.map(f => `- \`${f}\``).join('\n')}
If these files are supposed to not exist, please update your PR body to include "Skip New Tests".`;
  warn(output);
}

// Find changed React components
const changedComponents = modifiedFiles.filter(file => {
  const content = fs.readFileSync(file).toString();
  return content.includes('React');
});

// Check for images in PR description if new components added
if (changedComponents.length > 0 && !skipVisualDiff && !hasScreenShots) {
  const output = `Should there be images to represent these components:
  ${changedComponents.map(f => `- \`${f}\``).join('\n')}
  If these changes are not visual, please update your PR body to include "Skip Visual Diff".`;
  warn(output);
}

// Check that every component touched has a corresponding story
const correspondingStoriesForChangedComponents = uniq(
  changedComponents.map(f => {
    const newPath = path.dirname(f);
    return `${newPath}/__stories__/index.js`;
  })
);

const missingStories = correspondingStoriesForChangedComponents.filter(
  f => !fs.existsSync(f)
);

if (missingStories.length && !skipStories) {
  const output = `Missing Stories:
${missingStories.map(f => `- \`${f}\``).join('\n')}
If these stories should not exist, please update your PR body to include "Skip Stories".`;
  warn(output);
}