@codemod-utils/blueprints

Utilities for blueprints

What is it?

Are there files that you always need, in order to create or update projects? @codemod-utils/blueprints helps you define these files and provide user-specific data (context).

API

decideVersion

Returns the version that can be installed for a package.

Always favors the current version in the user's project (a no-op). Uses the latest version only if the project doesn't depend on the package yet.

[!NOTE] It is assumed that:

• You don't want to rely on a library such as latest-version. (The reasons are, your codemod would have an extra dependency and your tests may fail without stubs—more dependencies.)
• Before calling decideVersion, the codemod has computed dependencies (current dependencies of the user's project) and stored latestVersions (versions to install by default) somewhere.

First, pass latestVersions to decideVersion().

import { decideVersion } from '@codemod-utils/blueprints';

const latestVersions = new Map([
  ['embroider-css-modules', '1.0.0'],
  ['webpack', '5.89.0'],
]);

// Create a wrapper
function getVersion(packageName, options) {
  const { dependencies } = options;

  return decideVersion(packageName, {
    dependencies,
    latestVersions,
  });
}

Then, pass dependencies to decideVersion().

const options = {
  dependencies: new Map([
    ['webpack', '^5.82.0'],
  ]),
};

getVersion('embroider-css-modules', options); // '^1.0.0'
getVersion('webpack', options); // '^5.82.0' (no-op)

getFilePath

Returns where npx installs the codemod on the user's machine.

To read blueprint files, get the path to the blueprints folder.

/* src/utils/blueprints/blueprints-root.ts */
import { join } from 'node:path';

import { getFilePath } from '@codemod-utils/blueprints';

const fileURL = import.meta.url;

const blueprintsRoot = join(getFilePath(fileURL), '../../blueprints');

// '<some/absolute/path>/src/blueprints'

Afterwards, prepend the file path with blueprintsRoot.

import { readFileSync } from 'node:fs';
import { join } from 'node:path';

const blueprintFilePaths = ['LICENSE.md', 'README.md'];

blueprintFilePaths.forEach((blueprintFilePath) => {
  const blueprintFile = readFileSync(
    join(blueprintsRoot, blueprintFilePath),
    'utf8',
  );
});

processTemplate

Often, blueprints need context: If some condition is true, a file should be generated in a different way. You can embed logic with delimiters in the blueprint files, then use processTemplate to pass data.

There are 3 types of delimiters:

• Escape (<%- %>) - escape an HTML code
• Evaluate (<% %>) - evaluate a JavaScript code
• Interpolate (<%= %>) - substitute a value

First, create a blueprint file.

/* blueprints/__testAppLocation__/ember-cli-build.js */
'use strict';

const EmberApp = require('ember-cli/lib/broccoli/ember-app');

module.exports = function (defaults) {
  const app = new EmberApp(defaults, {
    // Add options here
    autoImport: {
      watchDependencies: ['<%= addon.name %>'],
    },<% if (testApp.hasTypeScript) { %>
    'ember-cli-babel': {
      enableTypeScriptTransform: true,
    },<% } %>
  });

  const { maybeEmbroider } = require('@embroider/test-setup');

  return maybeEmbroider(app);
};

Then, pass data to the file.

import { readFileSync } from 'node:fs';
import { join } from 'node:path';

import { processTemplate } from '@codemod-utils/blueprints';

// Read file
const blueprintFilePath = '__testAppLocation__/ember-cli-build.js';

const blueprintFile = readFileSync(
  join(blueprintsRoot, blueprintFilePath),
  'utf8',
);

// Process file
processTemplate(blueprintFile, {
  addon: {
    name: 'ember-container-query',
  },
  app: {
    hasTypeScript: true,
  },
});

Often, it is easy to miscalculate data and misplace the newline character \n . If you intend to publish your codemod, I recommend using @codemod-utils/tests (create and test file fixtures) to check the output and prevent regressions.

Compatibility

• Node.js v18 or above

Contributing

See the Contributing guide for details.

License

This project is licensed under the MIT License.