Full code snippets relative to the Medium story

buddybuild_postbuild.sh

#!/usr/bin/env bash

echo "Run custom test frameworks"

cd ..

# Create the directory expected by buddybuild
mkdir -p buddybuild_artifacts/Jest
mkdir -p buddybuild_artifacts/ESLint

# Run the ESLint command then the output transformation script
eslint src --format json > buddybuild_artifacts/ESLint/eslint.json
node eslint-output-adapter.js || exit 1

# Run the Jest command
jest --outputFile=buddybuild_artifacts/Jest/jest.json --json || exit 1

eslint-output-adapter.js

/*
 * This file rewrites the eslint JSON output to make it similar
 * to the Jest JSON output. So that buddybuild can understand it
 * and display a proper and relevant ESLint tab
 */

const util = require('util');
const fs = require('fs');

// Node 8 is needed
const readFile = util.promisify(fs.readFile);
const writeFile = util.promisify(fs.writeFile);

let errorCount = 0;

readFile('buddybuild_artifacts/ESLint/eslint.json')
  .then(JSON.parse)
  .then(eslintReport => {
    // 1. Create a single test suite report
    const output = {
      testResults: [
        {
          assertionResults: [],
        },
      ],
    };

    // 2. Populate with a test case for each file in the ESLint report
    eslintReport.forEach(entry => {
      errorCount += entry.errorCount ? 1 : 0; // Count only 1 error in case of multiple errors in the same file
      output.testResults[0].assertionResults.push({
        status: entry.errorCount ? 'failed' : 'passed',
        title: entry.filePath,
        failureMessages: entry.messages.map(
          // Transform the object-based ESLint message into a Jest-style string: 
          ({ ruleId, message, line, column }) => `Error ${ruleId} at ${line}${column}: ${message}`,
        ),
      });
    });

    // 3. Add Jest-style metadata
    // Global metadata
    output.numFailedTestSuites = errorCount ? 1 : 0;
    output.numFailedTests = errorCount;
    output.numPassedTestSuites = errorCount ? 0 : 1;
    output.numPassedTests = eslintReport.length - errorCount;
    output.numTotalTestSuites = 1;
    output.numTotalTests = eslintReport.length;
    output.success = !errorCount;

    // Test suite metadata
    output.testResults[0].status = errorCount ? 'failed' : 'passed';
    output.testResults[0].message = '';
    output.testResults[0].name = '';
    output.testResults[0].summary = '';

    return output;
  })
  .then(JSON.stringify)
  .then(output => writeFile('buddybuild_artifacts/ESLint/eslint.json', output))
  .then(() => {
    console.log('Eslint output transformation done');
    // Exit with an error code in case of ESLint error
    process.exit(errorCount ? 1 : 0);
  })
  .catch(err => {
    console.error('Error during Eslint output transformation', err);
    process.exit(1);
  });