build: tslint rule to ensure license banners are set (#5133)

build-config.js

@@ -9,10 +9,12 @@ const buildVersion = require('./package.json').version;
 
 /** License that will be placed inside of all created bundles. */
 const buildLicense = `/**
-  * @license Angular Material v${buildVersion}
-  * Copyright (c) 2017 Google, Inc. https://material.angular.io/
-  * License: MIT
-  */`;
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */`;
 
 module.exports = {
   projectVersion: buildVersion,

tools/tslint-rules/requireLicenseBannerRule.js

@@ -0,0 +1,56 @@
+const Lint = require('tslint');
+const path = require('path');
+const buildConfig = require('../../build-config');
+
+/** Paths to the directories that are public packages and should be validated. */
+const packageDirs = [
+  path.join(buildConfig.packagesDir, 'lib'),
+  path.join(buildConfig.packagesDir, 'cdk')
+];
+
+/** License banner that is placed at the top of every public TypeScript file. */
+const licenseBanner = buildConfig.licenseBanner;
+
+/** Failure message that will be shown if a license banner is missing. */
+const ERROR_MESSAGE = 'Missing license header in this TypeScript file. ' +
+  'Every TypeScript file of the library needs to have the Google license banner at the top.';
+
+/** TSLint fix that can be used to add the license banner easily. */
+const tslintFix = Lint.Replacement.appendText(0, licenseBanner + '\n\n');
+
+/**
+ * Rule that walks through all TypeScript files of public packages and shows failures if a
+ * file does not have the license banner at the top of the file.
+ */
+class Rule extends Lint.Rules.AbstractRule {
+
+  apply(sourceFile) {
+    return this.applyWithWalker(new RequireLicenseBannerWalker(sourceFile, this.getOptions()));
+  }
+}
+
+class RequireLicenseBannerWalker extends Lint.RuleWalker {
+
+  visitSourceFile(sourceFile) {
+    const filePath = path.join(buildConfig.projectDir, sourceFile.fileName);
+
+    // Do not check TypeScript source files that are not inside of a public package.
+    if (!packageDirs.some(packageDir => filePath.includes(packageDir))) {
+      return;
+    }
+
+    // Do not check source files inside of public packages that are spec or definition files.
+    if (filePath.endsWith('.spec.ts') || filePath.endsWith('.d.ts')) {
+      return;
+    }
+
+    const fileContent = sourceFile.getFullText();
+    const licenseCommentPos = fileContent.indexOf(licenseBanner);
+
+    if (licenseCommentPos !== 0) {
+      return this.addFailureAt(0, 0, ERROR_MESSAGE, tslintFix);
+    }
+  }
+}
+
+exports.Rule = Rule;

tslint.json

@@ -72,6 +72,7 @@
     // Disallows importing the whole RxJS library. Submodules can be still imported.
     "import-blacklist": [true, "rxjs"],
     // Avoids inconsistent linebreak styles in source files. Forces developers to use LF linebreaks.
-    "linebreak-style": [true, "LF"]
+    "linebreak-style": [true, "LF"],
+    "require-license-banner": true
   }
 }