fix(examples): form-field custom control example not working (#13043)

* Removes a workaround that allowed the secondary component of the form-field-custom-control to use the primary asset files (`form-field-custom-control-example.(html|css` are reserved for the primary example component). This workaround caused the example to not render properly inside of StackBlitz.
* Fixes that the build-example-module task does not properly detect stylesheet additional files.
* Depends on https://github.com/angular/material.angular.io/pull/516
Fixes #13021

src/material-examples/form-field-custom-control/form-field-custom-control-example.css

@@ -1,21 +1 @@
-div {
-  display: flex;
-}
-
-input {
-  border: none;
-  background: none;
-  padding: 0;
-  outline: none;
-  font: inherit;
-  text-align: center;
-}
-
-span {
-  opacity: 0;
-  transition: opacity 200ms;
-}
-
-:host.floating span {
-  opacity: 1;
-}
+/** No CSS for this example */

src/material-examples/form-field-custom-control/form-field-custom-control-example.html

@@ -1,7 +1,5 @@
-<div [formGroup]="parts">
-  <input class="area" formControlName="area" size="3">
-  <span>&ndash;</span>
-  <input class="exchange" formControlName="exchange" size="3">
-  <span>&ndash;</span>
-  <input class="subscriber" formControlName="subscriber" size="4">
-</div>
+<mat-form-field>
+  <my-tel-input placeholder="Phone number" required></my-tel-input>
+  <mat-icon matSuffix>phone</mat-icon>
+  <mat-hint>Include area code</mat-hint>
+</mat-form-field>

src/material-examples/form-field-custom-control/form-field-custom-control-example.ts

@@ -5,17 +5,24 @@ import {FormBuilder, FormGroup} from '@angular/forms';
 import {MatFormFieldControl} from '@angular/material';
 import {Subject} from 'rxjs';
 
+/** @title Form field with custom telephone number input control. */
+@Component({
+  selector: 'form-field-custom-control-example',
+  templateUrl: 'form-field-custom-control-example.html',
+  styleUrls: ['form-field-custom-control-example.css'],
+})
+export class FormFieldCustomControlExample {}
+
 /** Data structure for holding telephone number. */
 export class MyTel {
   constructor(public area: string, public exchange: string, public subscriber: string) {}
 }
 
-
 /** Custom `MatFormFieldControl` for telephone number input. */
 @Component({
   selector: 'my-tel-input',
-  templateUrl: 'form-field-custom-control-example.html',
-  styleUrls: ['form-field-custom-control-example.css'],
+  templateUrl: 'my-tel-input-example.html',
+  styleUrls: ['my-tel-input-example.css'],
   providers: [{provide: MatFormFieldControl, useExisting: MyTelInput}],
   host: {
     '[class.floating]': 'shouldLabelFloat',
@@ -109,17 +116,3 @@ export class MyTelInput implements MatFormFieldControl<MyTel>, OnDestroy {
     }
   }
 }
-
-
-/** @title Form field with custom telephone number input control. */
-@Component({
-  selector: 'form-field-custom-control-example',
-  template: `
-    <mat-form-field>
-      <my-tel-input placeholder="Phone number" required></my-tel-input>
-      <mat-icon matSuffix>phone</mat-icon>
-      <mat-hint>Include area code</mat-hint>
-    </mat-form-field>
-  `
-})
-export class FormFieldCustomControlExample {}

src/material-examples/form-field-custom-control/my-tel-input-example.css

@@ -0,0 +1,21 @@
+.my-tel-input-container {
+  display: flex;
+}
+
+.my-tel-input-element {
+  border: none;
+  background: none;
+  padding: 0;
+  outline: none;
+  font: inherit;
+  text-align: center;
+}
+
+.my-tel-input-spacer {
+  opacity: 0;
+  transition: opacity 200ms;
+}
+
+:host.floating .my-tel-input-spacer {
+  opacity: 1;
+}

src/material-examples/form-field-custom-control/my-tel-input-example.html

@@ -0,0 +1,7 @@
+<div [formGroup]="parts" class="my-tel-input-container">
+  <input class="my-tel-input-element" formControlName="area" size="3">
+  <span class="my-tel-input-spacer">&ndash;</span>
+  <input class="my-tel-input-element" formControlName="exchange" size="3">
+  <span class="my-tel-input-spacer">&ndash;</span>
+  <input class="my-tel-input-element" formControlName="subscriber" size="4">
+</div>

tools/gulp/tasks/example-module.ts

@@ -22,6 +22,7 @@ interface ParsedMetadata {
   component: string;
   title: string;
   templateUrl: string;
+  styleUrls: string[];
 }
 
 interface ParsedMetadataResults {
@@ -172,9 +173,16 @@ function parseExampleMetadata(fileName: string, sourceContent: string): ParsedMe
           if (decorator.expression.expression.text === 'Component') {
             for (const arg of decorator.expression.arguments) {
               for (const prop of arg.properties) {
-                const name = prop.name.text;
-                const value = prop.initializer.text;
-                meta[name] = value;
+                const propName = prop.name.text;
+
+                // Since additional files can be also stylesheets, we need to properly parse
+                // the styleUrls metadata property.
+                if (propName === 'styleUrls' && ts.isArrayLiteralExpression(prop.initializer)) {
+                  meta[propName] = prop.initializer.elements
+                    .map((literal: ts.StringLiteral) => literal.text);
+                } else {
+                  meta[propName] = prop.initializer.text;
+                }
               }
             }
 
@@ -204,8 +212,8 @@ task('build-examples-module', () => {
 
   for (const sourcePath of matchedFiles) {
     const sourceContent = fs.readFileSync(sourcePath, 'utf-8');
-    const { primaryComponent, secondaryComponents } =
-      parseExampleMetadata(sourcePath, sourceContent);
+    const {primaryComponent, secondaryComponents} =
+        parseExampleMetadata(sourcePath, sourceContent);
 
     if (primaryComponent) {
       // Generate a unique id for the component by converting the class name to dash-case.
@@ -226,9 +234,15 @@ task('build-examples-module', () => {
 
         for (const meta of secondaryComponents) {
           example.additionalComponents.push(meta.component);
+
           if (meta.templateUrl) {
             example.additionalFiles.push(meta.templateUrl);
           }
+
+          if (meta.styleUrls) {
+            example.additionalFiles.push(...meta.styleUrls);
+          }
+
           example.selectorName.push(meta.component);
         }
       }