feat(@schematics/angular): new 7.0.0 migration to remove polyfills

See PR angular#12346 for more information. This
PR migrates current CLI projects to the new polyfills introduced in that PR.

Author: hansl

packages/schematics/angular/migrations/migration-collection.json

@@ -9,6 +9,11 @@
       "version": "7.0.0-beta.0",
       "factory": "./update-7",
       "description": "Update an Angular CLI project to version 7."
+    },
+    "migration-03": {
+      "version": "7.0.0-rc.0",
+      "factory": "./update-7/index#polyfillMetadataRule",
+      "description": "Update an Angular CLI project to version 7."
     }
   }
-}
+}

packages/schematics/angular/migrations/update-7/index.ts

@@ -13,6 +13,7 @@ import {
 } from '../../utility/dependencies';
 import { latestVersions } from '../../utility/latest-versions';
 
+export { polyfillMetadataRule } from './polyfill-metadata';
 
 export default function(): Rule {
   return (tree, context) => {

packages/schematics/angular/migrations/update-7/polyfill-metadata.ts

@@ -0,0 +1,136 @@
+/**
+ * @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
+ */
+import { json } from '@angular-devkit/core';
+import { Rule, Tree, chain, noop } from '@angular-devkit/schematics';
+import * as ts from 'typescript';
+
+
+/**
+ * Remove the Reflect import from a polyfill file.
+ * @param tree The tree to use.
+ * @param path Path of the polyfill file found.
+ * @private
+ */
+function _removeReflectFromPolyfills(tree: Tree, path: string) {
+  const source = tree.read(path);
+  if (!source) {
+    return;
+  }
+
+  // Start the update of the file.
+  const recorder = tree.beginUpdate(path);
+
+  const sourceFile = ts.createSourceFile(path, source.toString(), ts.ScriptTarget.Latest);
+  const imports = (
+    sourceFile.statements
+      .filter(s => s.kind === ts.SyntaxKind.ImportDeclaration) as ts.ImportDeclaration[]
+  );
+
+  for (const i of imports) {
+    const module = i.moduleSpecifier.kind == ts.SyntaxKind.StringLiteral
+      && (i.moduleSpecifier as ts.StringLiteral).text;
+
+    switch (module) {
+      case 'core-js/es7/reflect':
+        recorder.remove(i.getStart(sourceFile), i.getWidth(sourceFile));
+        break;
+    }
+  }
+
+  tree.commitUpdate(recorder);
+}
+
+/**
+ * Update a project's target, maybe. Only if it's a builder supported and the options look right.
+ * This is a rule factory so we return the new rule (or noop if we don't support doing the change).
+ * @param root The root of the project source.
+ * @param targetObject The target information.
+ * @private
+ */
+function _updateProjectTarget(root: string, targetObject: json.JsonObject): Rule {
+  // Make sure we're using the correct builder.
+  if (targetObject.builder !== '@angular-devkit/build-angular:browser'
+      || !json.isJsonObject(targetObject.options)) {
+    return noop();
+  }
+  const options = targetObject.options;
+  if (typeof options.polyfills != 'string') {
+    return noop();
+  }
+
+  const polyfillsToUpdate = [`${root}/${options.polyfills}`];
+  const configurations = targetObject.configurations;
+  if (json.isJsonObject(configurations)) {
+    for (const configName of Object.keys(configurations)) {
+      const config = configurations[configName];
+
+      // Just in case, only do non-AOT configurations.
+      if (json.isJsonObject(config)
+          && typeof config.polyfills == 'string'
+          && config.aot !== true) {
+        polyfillsToUpdate.push(`${root}/${config.polyfills}`);
+      }
+    }
+  }
+
+  return chain(
+    polyfillsToUpdate.map(polyfillPath => {
+      return (tree: Tree) => _removeReflectFromPolyfills(tree, polyfillPath);
+    }),
+  );
+}
+
+/**
+ * Move the import reflect metadata polyfill from the polyfill file to the dev environment. This is
+ * not guaranteed to work, but if it doesn't it will result in no changes made.
+ */
+export function polyfillMetadataRule(): Rule {
+  return (tree) => {
+    // Simple. Take the ast of polyfills (if it exists) and find the import metadata. Remove it.
+    const angularConfigContent = tree.read('angular.json') || tree.read('.angular.json');
+    const rules: Rule[] = [];
+
+    if (!angularConfigContent) {
+      // Is this even an angular project?
+      return;
+    }
+
+    const angularJson = json.parseJson(angularConfigContent.toString(), json.JsonParseMode.Loose);
+
+    if (!json.isJsonObject(angularJson) || !json.isJsonObject(angularJson.projects)) {
+      // If that field isn't there, no use...
+      return;
+    }
+
+    // For all projects, for all targets, read the polyfill field, and read the environment.
+    for (const projectName of Object.keys(angularJson.projects)) {
+      const project = angularJson.projects[projectName];
+      if (!json.isJsonObject(project)) {
+        continue;
+      }
+      if (typeof project.root != 'string') {
+        continue;
+      }
+
+      const targets = project.targets || project.architect;
+      if (!json.isJsonObject(targets)) {
+        continue;
+      }
+
+      for (const targetName of Object.keys(targets)) {
+        const target = targets[targetName];
+        if (json.isJsonObject(target)) {
+          rules.push(_updateProjectTarget(project.root, target));
+        }
+      }
+    }
+
+    // Remove null or undefined rules.
+    return chain(rules);
+  };
+}

packages/schematics/angular/migrations/update-7/polyfill-metadata_spec.ts

@@ -0,0 +1,89 @@
+/**
+ * @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
+ */
+import { Action, EmptyTree } from '@angular-devkit/schematics';
+import { SchematicTestRunner, UnitTestTree } from '@angular-devkit/schematics/testing';
+
+// Randomly import stuff (including es6 and es7 reflects).
+const oldPolyfills = `
+/** IE9, IE10 and IE11 requires all of the following polyfills. **/
+// import 'core-js/es6/symbol';
+// import 'core-js/es6/object';
+import 'core-js/es6/function';
+import 'core-js/es6/parse-int';
+// import 'core-js/es6/parse-float';
+import 'core-js/es6/number';
+// import 'core-js/es6/math';
+// import 'core-js/es6/string';
+import 'core-js/es6/date';
+// import 'core-js/es6/array';
+// import 'core-js/es6/regexp';
+
+/** IE10 and IE11 requires the following for the Reflect API. */
+import 'core-js/es6/reflect';
+
+
+/** Evergreen browsers require these. **/
+// Used for reflect-metadata in JIT. If you use AOT (and only Angular decorators), you can remove.
+import 'core-js/es7/reflect';
+
+import 'web-animations-js';  // Run \`npm install --save web-animations-js\`.
+
+ (window as any).__Zone_disable_requestAnimationFrame = true; // disable patch requestAnimationFrame
+ (window as any).__Zone_disable_on_property = true; // disable patch onProperty such as onclick
+
+/***************************************************************************************************
+ * Zone JS is required by default for Angular itself.
+ */
+import 'zone.js/dist/zone';  // Included with Angular CLI.
+`;
+
+
+describe('polyfillMetadataRule', () => {
+  const schematicRunner = new SchematicTestRunner(
+    'migrations',
+    require.resolve('../migration-collection.json'),
+  );
+
+  let tree: UnitTestTree;
+
+  beforeEach(async () => {
+    tree = new UnitTestTree(new EmptyTree());
+    tree = await schematicRunner.runExternalSchematicAsync(
+      require.resolve('../../collection.json'), 'ng-new',
+      {
+        name: 'migration-test',
+        version: '1.2.3',
+        directory: '.',
+      },
+      tree,
+    ).toPromise();
+  });
+
+  it('is noop for new projects', async () => {
+    const mapToIdem = (x: Action) => {
+      const content = (x.kind == 'o' || x.kind == 'c') ? x.content.toString() : null;
+
+      return { ...x, content, id: -1 };
+    };
+
+    const expected = [...tree.actions.map(mapToIdem)];
+    const tree2 = await schematicRunner.runSchematicAsync('migration-03', {}, tree.branch())
+      .toPromise();
+
+    expect(tree2.actions.map(mapToIdem)).toEqual(expected);
+  });
+
+  it('should work as expected', async () => {
+    const polyfillPath = '/src/polyfills.ts';
+    tree.overwrite(polyfillPath, oldPolyfills);
+    const tree2 = await schematicRunner.runSchematicAsync('migration-03', {}, tree.branch())
+      .toPromise();
+
+    expect(tree2.readContent(polyfillPath)).not.toMatch(/import .*es7.*reflect.*;/);
+  });
+});