feat: add license compliance check tool

.license-checker.js

@@ -0,0 +1,12 @@
+'use strict';
+
+module.exports = {
+
+   permittedLicenses: [
+      'BSD-2-Clause',
+      'BSD-3-Clause',
+      'Python-2.0',
+      'BSD*',
+   ]
+
+};

README.md

@@ -158,6 +158,42 @@ possible that some processes in some projects could fail when the wrong version
 is enabled in the developer's environment. This helps eliminate one factor from the
 equation when troubleshooting.
 
+### License Compliance Checker Tool
+
+This project contains a tool to verify that the licenses used by libraries in our
+projects that contain NPM dependencies are among our list of accepted licenses. To
+view the list of accepted licenses, see the `ALLOWED_LICENSES` list in:
+[check-license-compliance.js](scripts/check-license-compliance.js)
+
+To use this tool, `@silvermine/standardization` must be installed in your project:
+
+`npm i -DE @silvermine/standardization`
+
+You should then be able to run the tool in a NPM script:
+
+```json
+{
+   "scripts": {
+      "check-license-compliance": "check-license-compliance"
+   }
+}
+```
+
+The tool also allows you to configure exceptions for license types using a configuration
+file. To configure these exceptions, add a file called `.license-checker.js` to the root
+of your project with the following contents:
+
+```cjs
+'use strict';
+
+module.exports = {
+
+   permittedLicenses: [ 'My-Custom-License' ]
+
+};
+
+```
+
 ### Executing ESLint
 
 When ESLint is needed for a project, add an `eslint` task to package.json, and execute it

package.json

@@ -11,7 +11,11 @@
     "release:finalize": "node ./scripts/release.js finalize",
     "markdownlint": "markdownlint-cli2",
     "eslint": "eslint .",
-    "standards": "npm run commitlint && npm run eslint && npm run markdownlint"
+    "check-license-compliance": "node scripts/check-license-compliance.js",
+    "standards": "npm run commitlint && npm run check-license-compliance && npm run eslint && npm run markdownlint"
+  },
+  "bin": {
+    "check-license-compliance": "scripts/check-license-compliance.js"
   },
   "repository": {
     "type": "git",

scripts/check-license-compliance.js

@@ -0,0 +1,85 @@
+#! /usr/bin/env node
+'use strict';
+/* eslint no-console: [ "error", { allow: [ "info", "warn", "error", "table" ] } ] */
+const { init } = require('license-checker'),
+      process = require('process'),
+      util = require('util'),
+      initLicenseChecker = util.promisify(init),
+      packageDirectory = require('pkg-dir');
+
+const DEFAULT_PERMITTED_LICENSES = [
+   'MIT',
+   'ISC',
+   'Apache-2.0',
+   '(MIT OR Apache-2.0)',
+   'Public Domain',
+   'CC-BY-3.0',
+];
+
+(async () => {
+   const projectDirectoryPath = await packageDirectory(),
+         projectConfigPath = `${projectDirectoryPath}/.license-checker.js`,
+         licenseRecord = {};
+
+   let configuredPermittedLicenses = [],
+       moduleInfoReport,
+       unsupportedLicenses;
+
+   console.info('Project package.json located at path:', projectDirectoryPath);
+
+   try {
+      // eslint-disable-next-line global-require
+      const config = require(projectConfigPath);
+
+      configuredPermittedLicenses = config.permittedLicenses;
+
+      console.info(`Using configured allow-list at path ${projectConfigPath}`);
+      console.info('Allowing additional licenses:', configuredPermittedLicenses.join(', '));
+   } catch(e) {
+      console.error(e);
+      console.info('A config for license checker was not provided or was not found.');
+   }
+
+   try {
+      moduleInfoReport = await initLicenseChecker({
+         start: process.cwd(),
+      });
+   } catch(e) {
+      console.error('Could not initialize license-checker', e);
+      process.exitCode = 1;
+      return;
+   }
+
+   Object
+      .keys(moduleInfoReport)
+      .forEach((moduleName) => {
+         const licenses = moduleInfoReport[moduleName].licenses;
+
+         licenseRecord[moduleName] = {
+            module: moduleName,
+            license: licenses || 'UNLICENSED',
+            ...moduleInfoReport[moduleName],
+         };
+      });
+
+   console.info(`This project has ${Object.values(licenseRecord).length} licenses.`);
+
+   unsupportedLicenses = Object.values(licenseRecord).filter((record) => {
+      return !DEFAULT_PERMITTED_LICENSES.includes(record.license) && !configuredPermittedLicenses.includes(record.license);
+   });
+
+   if (unsupportedLicenses.length > 0) {
+      console.error(`${unsupportedLicenses.length} unsupported licenses found:`);
+
+      const errors = unsupportedLicenses
+         .map((record) => {
+            return {
+               'Module Name': record.module,
+               'Unsupported License': record.license,
+            };
+         });
+
+      console.table(errors);
+      process.exitCode = 1;
+   }
+})();