feat(ivy): support styleUrls in ngtsc (#27357)

This commit adds support for resolution of styleUrls to ngtsc. Previously
this field was never read, and so components with styleUrls would appear
unstyled after compilation.

PR Close #27357

packages/compiler-cli/src/ngtsc/annotations/src/component.ts

@@ -57,6 +57,7 @@ export class ComponentDecoratorHandler implements
   preanalyze(node: ts.ClassDeclaration, decorator: Decorator): Promise<void>|undefined {
     const meta = this._resolveLiteral(decorator);
     const component = reflectObjectLiteral(meta);
+    const promises: Promise<void>[] = [];
 
     if (this.resourceLoader.preload !== undefined && component.has('templateUrl')) {
       const templateUrlExpr = component.get('templateUrl') !;
@@ -66,10 +67,28 @@ export class ComponentDecoratorHandler implements
             ErrorCode.VALUE_HAS_WRONG_TYPE, templateUrlExpr, 'templateUrl must be a string');
       }
       const url = path.posix.resolve(path.dirname(node.getSourceFile().fileName), templateUrl);
-      return this.resourceLoader.preload(url);
+      const promise = this.resourceLoader.preload(url);
+      if (promise !== undefined) {
+        promises.push(promise);
       }
+    }
+
+    const styleUrls = this._extractStyleUrls(component);
+    if (this.resourceLoader.preload !== undefined && styleUrls !== null) {
+      for (const styleUrl of styleUrls) {
+        const url = path.posix.resolve(path.dirname(node.getSourceFile().fileName), styleUrl);
+        const promise = this.resourceLoader.preload(url);
+        if (promise !== undefined) {
+          promises.push(promise);
+        }
+      }
+    }
+    if (promises.length !== 0) {
+      return Promise.all(promises).then(() => undefined);
+    } else {
       return undefined;
     }
+  }
 
   analyze(node: ts.ClassDeclaration, decorator: Decorator): AnalysisOutput<ComponentHandlerData> {
     const meta = this._resolveLiteral(decorator);
@@ -186,6 +205,14 @@ export class ComponentDecoratorHandler implements
       styles = parseFieldArrayValue(component, 'styles', this.reflector, this.checker);
     }
 
+    let styleUrls = this._extractStyleUrls(component);
+    if (styleUrls !== null) {
+      if (styles === null) {
+        styles = [];
+      }
+      styles.push(...styleUrls.map(styleUrl => this.resourceLoader.load(styleUrl)));
+    }
+
     let encapsulation: number = 0;
     if (component.has('encapsulation')) {
       encapsulation = parseInt(staticallyResolve(
@@ -282,4 +309,18 @@ export class ComponentDecoratorHandler implements
     this.literalCache.set(decorator, meta);
     return meta;
   }
+
+  private _extractStyleUrls(component: Map<string, ts.Expression>): string[]|null {
+    if (!component.has('styleUrls')) {
+      return null;
+    }
+
+    const styleUrlsExpr = component.get('styleUrls') !;
+    const styleUrls = staticallyResolve(styleUrlsExpr, this.reflector, this.checker);
+    if (!Array.isArray(styleUrls) || !styleUrls.every(url => typeof url === 'string')) {
+      throw new FatalDiagnosticError(
+          ErrorCode.VALUE_HAS_WRONG_TYPE, styleUrlsExpr, 'styleUrls must be an array of strings');
+    }
+    return styleUrls as string[];
+  }
 }

packages/compiler-cli/test/ngtsc/ngtsc_spec.ts

@@ -89,6 +89,26 @@ describe('ngtsc behavioral tests', () => {
     expect(jsContents).toContain('Hello World');
   });
 
+  it('should compile components with styleUrls', () => {
+    env.tsconfig();
+    env.write('test.ts', `
+        import {Component} from '@angular/core';
+
+        @Component({
+          selector: 'test-cmp',
+          styleUrls: ['./dir/style.css'],
+          template: '',
+        })
+        export class TestCmp {}
+    `);
+    env.write('dir/style.css', ':host { background-color: blue; }');
+
+    env.driveMain();
+
+    const jsContents = env.getContents('test.js');
+    expect(jsContents).toContain('background-color: blue');
+  });
+
   it('should compile NgModules without errors', () => {
     env.tsconfig();
     env.write('test.ts', `