check-compatibility-with-govuk-frontend-version.js

// prototypes load and compile a subset of hmrc-frontend styles using their
// own version of govuk-frontend, if their version of govuk-frontend is
// lower than 5.4.0 then the compilation of styles will fail with an error
// that can be hard for interaction designers to debug, we would like to
// give them a warning on installation so that they don't get stuck later
// when trying to use the hmrc-frontend styles.
const fs = require('fs');
const path = require('path');

function hmrcFrontendDisableCompatibilityCheck() {
  return (process.env.npm_config_hmrc_frontend_disable_compatibility_check || process.env.HMRC_FRONTEND_DISABLE_COMPATIBILITY_CHECK) === 'true';
}

function semverGreaterThanOrEqualTo(a, b) {
  const [aMaj, aMin, aPat] = a.split('.').map(Number);
  const [bMaj, bMin, bPat] = b.split('.').map(Number);
  return ((aMaj - bMaj) || (aMin - bMin) || (aPat - bPat)) >= 0;
}

function withinPrototypeKitAndUsingIncompatibleGovukFrontendVersion() {
  const projectDir = process.env.INIT_CWD || process.cwd();
  const projectPackagePath = path.join(projectDir, 'package.json');
  const projectPackageJson = JSON.parse(fs.readFileSync(projectPackagePath, 'utf8'));

  if (
    !projectPackageJson.dependencies
    || !projectPackageJson.dependencies['govuk-frontend']
    || !projectPackageJson.dependencies['govuk-prototype-kit']
  ) {
    process.exit(0);
  }

  const currentVersionInProject = projectPackageJson.dependencies['govuk-frontend'].replace(/[^0-9.]/g, '');
  const minimumGovukFrontendVersion = '6.0.0';

  return (!semverGreaterThanOrEqualTo(currentVersionInProject, minimumGovukFrontendVersion));
}

try {
  if (hmrcFrontendDisableCompatibilityCheck()) {
    process.exit(0);
  }
  if (withinPrototypeKitAndUsingIncompatibleGovukFrontendVersion()) {
    // eslint-disable-next-line no-console
    process.stderr.write(`
    Hello friend, looks like your prototype is using a version of
    govuk-frontend lower than v6.0.0, which is the minimum version
    compatible to automatically compile and load the styles for the
    version of hmrc-frontend you're installing with the govuk-prototype-kit.

    You can silence this warning by setting the environment variable
    HMRC_FRONTEND_DISABLE_COMPATIBILITY_CHECK=true.
      - PlatUI
    -------------------------------------------
            \\   ^__^
            \\  (oo)_______
                (__)       )\\/\\
                    ||----w |
                    ||     ||
    - PlatMooI the PlatUI Helper Cow
    `);
    process.exit(1);
  } else {
    process.exit(0);
  }
} catch (err) {
  process.exit(0);
}