feat(example-viewer): support rendering additional files (angular#516)

* Currently we only render the `HTML`, `TS` and `CSS` files in the view-source tab group. This is fine for most examples, but there are also examples like the `form-field-custom-control` that prefer to have the template of the "custom control" externally. We should support rendering these additional files in the tab group instead of just magically adding them to the external StackBlitz that will be generated.

Related to angular#13021

package.json

@@ -20,13 +20,13 @@
   "private": true,
   "dependencies": {
     "@angular/animations": "^6.0.9",
-    "@angular/cdk": "^6.4.6",
+    "@angular/cdk": "^6.4.7",
     "@angular/common": "^6.0.9",
     "@angular/compiler": "^6.0.9",
     "@angular/core": "^6.0.9",
     "@angular/forms": "^6.0.9",
     "@angular/http": "^6.0.9",
-    "@angular/material": "^6.4.6",
+    "@angular/material": "^6.4.7",
     "@angular/material-moment-adapter": "^6.4.6",
     "@angular/platform-browser": "^6.0.9",
     "@angular/platform-browser-dynamic": "^6.0.9",

src/app/shared/example-viewer/example-viewer.html

@@ -17,16 +17,15 @@
 
   <div class="docs-example-viewer-source" *ngIf="showSource">
     <mat-tab-group>
-      <!-- TODO(jelbourn): don't hard-code the html + ts + css structure -->
-      <mat-tab *ngFor="let extension of ['HTML', 'TS', 'CSS']" [label]="extension">
+      <mat-tab *ngFor="let tabName of _getExampleTabNames()" [label]="tabName">
         <div class="docs-example-source-wrapper">
           <button mat-icon-button type="button" class="docs-example-source-copy"
                   title="Copy example source" aria-label="Copy example source to clipboard"
                   (click)="copySource(viewer.textContent)">
             <mat-icon>content_copy</mat-icon>
           </button>
           <pre class="docs-example-source"><doc-viewer
-              #viewer [documentUrl]="exampleFileUrl(extension)"></doc-viewer></pre>
+              #viewer [documentUrl]="exampleTabs[tabName]"></doc-viewer></pre>
         </div>
       </mat-tab>
     </mat-tab-group>

src/app/shared/example-viewer/example-viewer.spec.ts

@@ -61,12 +61,12 @@ describe('ExampleViewer', () => {
     expect(data).toEqual(EXAMPLE_COMPONENTS[exampleKey] as any);
   }));
 
-  it('should log message about missing example', async(() => {
-    spyOn(console, 'log');
+  it('should print an error message about missing example', async(() => {
+    spyOn(console, 'error');
     component.example = 'foobar';
     fixture.detectChanges();
-    expect(console.log).toHaveBeenCalled();
-    expect(console.log).toHaveBeenCalledWith('MISSING EXAMPLE: ', 'foobar');
+    expect(console.error).toHaveBeenCalled();
+    expect(console.error).toHaveBeenCalledWith('Could not find example: foobar');
   }));
 
   it('should return assets path for example based on extension', async(() => {
@@ -77,13 +77,38 @@ describe('ExampleViewer', () => {
     // get example file path for each extension
     const extensions = ['ts', 'css', 'html'];
     const basePath = '/assets/examples/';
-    extensions.forEach(ext => {
-      const expected = `${basePath}${exampleKey}-example-${ext}.html`;
-      const actual = component.exampleFileUrl(ext);
+
+    extensions.forEach(extension => {
+      const expected = `${basePath}${exampleKey}-example-${extension}.html`;
+      const actual = component.exampleTabs[extension.toUpperCase()];
+
       expect(actual).toEqual(expected);
     });
   }));
 
+  describe('view-source tab group', () => {
+
+    it('should only render HTML, TS and CSS files if no additional files are specified', () => {
+      component.example = exampleKey;
+      fixture.detectChanges();
+
+      expect(component._getExampleTabNames()).toEqual(['HTML', 'TS', 'CSS']);
+    });
+
+    it('should be able to render additional files', () => {
+      EXAMPLE_COMPONENTS['additional-files'] = {
+        additionalFiles: ['some-additional-file.html'],
+        ...EXAMPLE_COMPONENTS[exampleKey]
+      };
+
+      component.example = 'additional-files';
+      fixture.detectChanges();
+
+      expect(component._getExampleTabNames())
+        .toEqual(['HTML', 'TS', 'CSS', 'some-additional-file.html']);
+    });
+  });
+
   describe('copy button', () => {
     let button: HTMLElement;
 

src/app/shared/example-viewer/example-viewer.ts

@@ -5,6 +5,8 @@ import {ComponentPortal} from '@angular/cdk/portal';
 import {EXAMPLE_COMPONENTS, LiveExample} from '@angular/material-examples';
 import {CopierService} from '../copier/copier.service';
 
+/** Regular expression that matches a file name and its extension */
+const fileExtensionRegex = /(.*)\.(\w+)/;
 
 @Component({
   selector: 'example-viewer',
@@ -15,46 +17,66 @@ export class ExampleViewer {
   /** Component portal for the currently displayed example. */
   selectedPortal: ComponentPortal<any>;
 
-  /** String key of the currently displayed example. */
-  _example: string;
+  /** Map of example files that should be displayed in the view-source tab. */
+  exampleTabs: {[tabName: string]: string};
 
+  /** Data for the currently selected example. */
   exampleData: LiveExample;
 
   /** Whether the source for the example is being displayed. */
   showSource = false;
 
-  constructor(
-    private snackbar: MatSnackBar,
-    private copier: CopierService) { }
-
-  get example() {
-    return this._example;
-  }
-
+  /** String key of the currently displayed example. */
   @Input()
-  set example(example: string) {
-    if (example && EXAMPLE_COMPONENTS[example]) {
-      this._example = example;
-      this.exampleData = EXAMPLE_COMPONENTS[example];
+  get example() { return this._example; }
+  set example(exampleName: string) {
+    if (exampleName && EXAMPLE_COMPONENTS[exampleName]) {
+      this._example = exampleName;
+      this.exampleData = EXAMPLE_COMPONENTS[exampleName];
       this.selectedPortal = new ComponentPortal(this.exampleData.component);
+      this._generateExampleTabs();
     } else {
-      console.log('MISSING EXAMPLE: ', example);
+      console.error(`Could not find example: ${exampleName}`);
     }
   }
+  private _example: string;
+
+  constructor(private snackbar: MatSnackBar,private copier: CopierService) {}
 
   toggleSourceView(): void {
     this.showSource = !this.showSource;
   }
 
-  exampleFileUrl(extension: string) {
-    return `/assets/examples/${this.example}-example-${extension.toLowerCase()}.html`;
-  }
-
   copySource(text: string) {
     if (this.copier.copyText(text)) {
       this.snackbar.open('Code copied', '', {duration: 2500});
     } else {
       this.snackbar.open('Copy failed. Please try again!', '', {duration: 2500});
     }
   }
+
+  _getExampleTabNames() {
+    return Object.keys(this.exampleTabs);
+  }
+
+  private resolveExampleFile(fileName: string) {
+    return `/assets/examples/${fileName}`;
+  }
+
+  private _generateExampleTabs() {
+    this.exampleTabs = {
+      HTML: this.resolveExampleFile(`${this.example}-example-html.html`),
+      TS: this.resolveExampleFile(`${this.example}-example-ts.html`),
+      CSS: this.resolveExampleFile(`${this.example}-example-css.html`),
+    };
+
+    const additionalFiles = this.exampleData.additionalFiles || [];
+
+    additionalFiles.forEach(fileName => {
+      // Since the additional files refer to the original file name, we need to transform
+      // the file name to match the highlighted HTML file that displays the source.
+      const fileSourceName = fileName.replace(fileExtensionRegex, '$1-$2.html');
+      this.exampleTabs[fileName] = this.resolveExampleFile(fileSourceName);
+    })
+  }
 }