fix(ng-add): allow using noop animations (#13429)

* Currently we always install `@angular/animations` and add the `BrowserAnimationsModule` to the project module. There should be a prompt/option that allows developers to use the `NoopAnimationsModule`.

* Also no longer adds the `BrowserAnimationsModule` if the project already uses the `NoopAnimationsModule` (avoiding magic). Same applies for the `NoopAnimationsModule`. We won't add the noop animations module if the browser animations module is configured.

Handle existing animation modules

src/cdk/schematics/utils/ast/ng-module-imports.ts

@@ -0,0 +1,78 @@
+/**
+ * @license
+ * Copyright Google LLC 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 {Tree} from '@angular-devkit/schematics';
+import * as ts from 'typescript';
+
+/**
+ * Whether the Angular module in the given path imports the specifed module class name.
+ */
+export function hasNgModuleImport(tree: Tree, modulePath: string, className: string): boolean {
+  const moduleFileContent = tree.read(modulePath);
+
+  if (!moduleFileContent) {
+    throw new Error(`Could not read Angular module file: ${modulePath}`);
+  }
+
+  const parsedFile = ts.createSourceFile(modulePath, moduleFileContent.toString(),
+      ts.ScriptTarget.Latest, true);
+  let ngModuleMetadata: ts.ObjectLiteralExpression | null = null;
+
+  const findModuleDecorator = (node: ts.Node) => {
+    if (ts.isDecorator(node) && ts.isCallExpression(node.expression) &&
+        isNgModuleCallExpression(node.expression)) {
+      ngModuleMetadata = node.expression.arguments[0] as ts.ObjectLiteralExpression;
+      return;
+    }
+
+    ts.forEachChild(node, findModuleDecorator);
+  };
+
+  ts.forEachChild(parsedFile, findModuleDecorator);
+
+  if (!ngModuleMetadata) {
+    throw new Error(`Could not find NgModule declaration inside: "${modulePath}"`);
+  }
+
+  for (let property of ngModuleMetadata!.properties) {
+    if (!ts.isPropertyAssignment(property) || property.name.getText() !== 'imports' ||
+        !ts.isArrayLiteralExpression(property.initializer)) {
+      continue;
+    }
+
+    if (property.initializer.elements.some(element => element.getText() === className)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+/**
+ * Resolves the last identifier that is part of the given expression. This helps resolving
+ * identifiers of nested property access expressions (e.g. myNamespace.core.NgModule).
+ */
+function resolveIdentifierOfExpression(expression: ts.Expression): ts.Identifier | null {
+  if (ts.isIdentifier(expression)) {
+    return expression;
+  } else if (ts.isPropertyAccessExpression(expression)) {
+    return resolveIdentifierOfExpression(expression.expression);
+  }
+  return null;
+}
+
+/** Whether the specified call expression is referring to a NgModule definition. */
+function isNgModuleCallExpression(callExpression: ts.CallExpression): boolean {
+  if (!callExpression.arguments.length ||
+      !ts.isObjectLiteralExpression(callExpression.arguments[0])) {
+    return false;
+  }
+
+  const decoratorIdentifier = resolveIdentifierOfExpression(callExpression.expression);
+  return decoratorIdentifier ? decoratorIdentifier.text === 'NgModule' : false;
+}

src/cdk/schematics/utils/index.ts

@@ -7,6 +7,7 @@
  */
 
 export * from './ast';
+export * from './ast/ng-module-imports';
 export * from './build-component';
 export * from './get-project';
 export * from './parse5-element';

src/lib/schematics/ng-add/index.spec.ts

@@ -3,6 +3,7 @@ import {WorkspaceProject} from '@angular-devkit/core/src/workspace';
 import {Tree} from '@angular-devkit/schematics';
 import {SchematicTestRunner} from '@angular-devkit/schematics/testing';
 import {
+  addModuleImportToRootModule,
   createTestApp,
   getProjectFromWorkspace,
   getProjectStyleFile,
@@ -27,7 +28,19 @@ describe('ng-add schematic', () => {
         `Expected "${filePath}" to be added to the project styles in the workspace.`);
   }
 
+  /** Removes the specified dependency from the /package.json in the given tree. */
+  function removePackageJsonDependency(tree: Tree, dependencyName: string) {
+    const packageContent = JSON.parse(getFileContent(tree, '/package.json'));
+    delete packageContent.dependencies[dependencyName];
+    tree.overwrite('/package.json', JSON.stringify(packageContent, null, 2));
+  }
+
   it('should update package.json', () => {
+    // By default, the Angular workspace schematic sets up "@angular/animations". In order
+    // to verify that we would set up the dependency properly if someone doesn't have the
+    // animations installed already, we remove the animations dependency explicitly.
+    removePackageJsonDependency(appTree, '@angular/animations');
+
     const tree = runner.runSchematic('ng-add', {}, appTree);
     const packageJson = JSON.parse(getFileContent(tree, '/package.json'));
     const dependencies = packageJson.dependencies;
@@ -142,4 +155,56 @@ describe('ng-add schematic', () => {
         'Expected the project main file to not contain a HammerJS import.');
     });
   });
+
+  describe('animations enabled', () => {
+    it('should add the BrowserAnimationsModule to the project module', () => {
+      const tree = runner.runSchematic('ng-add-setup-project', {}, appTree);
+      const fileContent = getFileContent(tree, '/projects/material/src/app/app.module.ts');
+
+      expect(fileContent).toContain('BrowserAnimationsModule',
+        'Expected the project app module to import the "BrowserAnimationsModule".');
+    });
+
+    it('should not add BrowserAnimationsModule if NoopAnimationsModule is set up', () => {
+      const workspace = getWorkspace(appTree);
+      const project = getProjectFromWorkspace(workspace);
+
+      // Simulate the case where a developer uses `ng-add` on an Angular CLI project which already
+      // explicitly uses the `NoopAnimationsModule`. It would be wrong to forcibly enable browser
+      // animations without knowing what other components would be affected. In this case, we
+      // just print a warning message.
+      addModuleImportToRootModule(appTree, 'NoopAnimationsModule',
+          '@angular/platform-browser/animations', project);
+
+      spyOn(console, 'warn');
+      runner.runSchematic('ng-add-setup-project', {}, appTree);
+
+      expect(console.warn).toHaveBeenCalledWith(
+        jasmine.stringMatching(/Could not set up "BrowserAnimationsModule"/));
+    });
+  });
+
+  describe('animations disabled', () => {
+    it('should add the NoopAnimationsModule to the project module', () => {
+      const tree = runner.runSchematic('ng-add-setup-project', {animations: false}, appTree);
+      const fileContent = getFileContent(tree, '/projects/material/src/app/app.module.ts');
+
+      expect(fileContent).toContain('NoopAnimationsModule',
+        'Expected the project app module to import the "NoopAnimationsModule".');
+    });
+
+    it('should not add NoopAnimationsModule if BrowserAnimationsModule is set up', () => {
+      const workspace = getWorkspace(appTree);
+      const project = getProjectFromWorkspace(workspace);
+
+      // Simulate the case where a developer uses `ng-add` on an Angular CLI project which already
+      // explicitly uses the `BrowserAnimationsModule`. It would be wrong to forcibly change
+      // to noop animations.
+      const fileContent = addModuleImportToRootModule(appTree, 'BrowserAnimationsModule',
+          '@angular/platform-browser/animations', project);
+
+      expect(fileContent).not.toContain('NoopAnimationsModule',
+          'Expected the project app module to not import the "NoopAnimationsModule".');
+    });
+  });
 });

src/lib/schematics/ng-add/schema.json

@@ -22,6 +22,12 @@
       "default": true,
       "description": "Whether gesture support should be set up or not.",
       "x-prompt": "Set up HammerJS for gesture recognition?"
+    },
+    "animations": {
+      "type": "boolean",
+      "default": true,
+      "description": "Whether Angular browser animations should be set up or not.",
+      "x-prompt": "Set up browser animations for Angular Material?"
     }
   },
   "required": []

src/lib/schematics/ng-add/schema.ts

@@ -14,6 +14,9 @@ export interface Schema {
   /** Whether gesture support should be set up or not. */
   gestures: boolean;
 
+  /** Whether Angular browser animations should be set up or not. */
+  animations: boolean;
+
   /** Name of pre-built theme to install. */
   theme: 'indigo-pink' | 'deeppurple-amber' | 'pink-bluegrey' | 'purple-green' | 'custom';
 }

src/lib/schematics/ng-add/setup-project.ts

@@ -10,15 +10,25 @@ import {chain, noop, Rule, SchematicsException, Tree} from '@angular-devkit/sche
 import {
   addModuleImportToRootModule,
   getProjectFromWorkspace,
+  getProjectMainFile,
   getProjectStyleFile,
+  hasNgModuleImport,
 } from '@angular/cdk/schematics';
+import {red, bold} from 'chalk';
 import {getWorkspace} from '@schematics/angular/utility/config';
+import {getAppModulePath} from '@schematics/angular/utility/ng-ast-utils';
 import * as parse5 from 'parse5';
 import {addFontsToIndex} from './fonts/material-fonts';
 import {addHammerJsToMain} from './gestures/hammerjs-import';
 import {Schema} from './schema';
 import {addThemeToAppStyles} from './theming/theming';
 
+/** Name of the Angular module that enables Angular browser animations. */
+const browserAnimationsModuleName = 'BrowserAnimationsModule';
+
+/** Name of the module that switches Angular animations to a noop implementation. */
+const noopAnimationsModuleName = 'NoopAnimationsModule';
+
 /**
  * Scaffolds the basics of a Angular Material application, this includes:
  *  - Add Packages to package.json
@@ -33,21 +43,43 @@ export default function(options: Schema): Rule {
 
   return chain([
     options && options.gestures ? addHammerJsToMain(options) : noop(),
+    addAnimationsModule(options),
     addThemeToAppStyles(options),
-    addAnimationRootConfig(options),
     addFontsToIndex(options),
     addMaterialAppStyles(options),
   ]);
 }
 
-/** Add browser animation module to the app module file. */
-function addAnimationRootConfig(options: Schema) {
+/**
+ * Adds an animation module to the root module of the specified project. In case the "animations"
+ * option is set to false, we still add the `NoopAnimationsModule` because otherwise various
+ * components of Angular Material will throw an exception.
+ */
+function addAnimationsModule(options: Schema) {
   return (host: Tree) => {
     const workspace = getWorkspace(host);
     const project = getProjectFromWorkspace(workspace, options.project);
+    const appModulePath = getAppModulePath(host, getProjectMainFile(project));
 
-    addModuleImportToRootModule(host, 'BrowserAnimationsModule',
-      '@angular/platform-browser/animations', project);
+    if (options.animations) {
+      // In case the project explicitly uses the NoopAnimationsModule, we should print a warning
+      // message that makes the user aware of the fact that we won't automatically set up
+      // animations. If we would add the BrowserAnimationsModule while the NoopAnimationsModule
+      // is already configured, we would cause unexpected behavior and runtime exceptions.
+      if (hasNgModuleImport(host, appModulePath, noopAnimationsModuleName)) {
+        return console.warn(red(`Could not set up "${bold(browserAnimationsModuleName)}" ` +
+            `because "${bold(noopAnimationsModuleName)}" is already imported. Please manually ` +
+            `set up browser animations.`));
+      }
+
+      addModuleImportToRootModule(host, browserAnimationsModuleName,
+          '@angular/platform-browser/animations', project);
+    } else if (!hasNgModuleImport(host, appModulePath, browserAnimationsModuleName)) {
+      // Do not add the NoopAnimationsModule module if the project already explicitly uses
+      // the BrowserAnimationsModule.
+      addModuleImportToRootModule(host, noopAnimationsModuleName,
+        '@angular/platform-browser/animations', project);
+    }
 
     return host;
   };