feat(aio): code copy button has tooltip and aria-label

Based on optional title passed in from parent element such as CodeExample or CodeTabs.
Darkens uncovered copy button slightly as recommended for a11y.
PR #16808

aio/src/app/embedded/code/code-example.component.ts

@@ -18,7 +18,9 @@ import { getBoolFromAttribute } from 'app/shared/attribute-utils';
   template: `
     <header *ngIf="title">{{title}}</header>
     <aio-code [ngClass]="classes" [code]="code"
-    [language]="language" [linenums]="linenums" [path]="path" [region]="region" [hideCopy]="hideCopy"></aio-code>
+    [language]="language" [linenums]="linenums"
+    [path]="path" [region]="region"
+    [hideCopy]="hideCopy" [title]="title"></aio-code>
   `
 })
 export class CodeExampleComponent implements OnInit {

aio/src/app/embedded/code/code-tabs.component.ts

@@ -27,7 +27,8 @@ export interface TabInfo {
         <span class="{{tab.class}}">{{ tab.title }}</span>
       </ng-template>
       <aio-code [code]="tab.code" [language]="tab.language" [linenums]="tab.linenums"
-      [path]="tab.path" [region]="tab.region" class="{{ tab.class }}"></aio-code>
+      [path]="tab.path" [region]="tab.region" [title]="tab.title"
+      class="{{ tab.class }}"></aio-code>
     </md-tab>
   </md-tab-group>
   `

aio/src/app/embedded/code/code.component.spec.ts

@@ -179,26 +179,45 @@ describe('CodeComponent', () => {
 
   describe('copy button', () => {
 
+    function getButton() {
+      const btnDe = fixture.debugElement.query(By.css('button'));
+      return btnDe ? btnDe.nativeElement : null;
+    }
+
     it('should be hidden if the `hideCopy` input is true', () => {
       hostComponent.hideCopy = true;
       fixture.detectChanges();
-      expect(fixture.debugElement.query(By.css('button'))).toBe(null);
+      expect(getButton()).toBe(null);
+    });
+
+    it('should have title', () => {
+      fixture.detectChanges();
+      expect(getButton().title).toBe('Copy code snippet');
+    });
+
+    it('should have no aria-label by default', () => {
+      fixture.detectChanges();
+      expect(getButton().getAttribute('aria-label')).toBe('');
+    });
+
+    it('should have aria-label explaining what is being copied when title passed in', () => {
+      hostComponent.title = 'a/b/c/foo.ts';
+      fixture.detectChanges();
+      expect(getButton().getAttribute('aria-label')).toContain(hostComponent.title);
     });
 
     it('should call copier service when clicked', () => {
       const copierService: CopierService = TestBed.get(CopierService);
       const spy = spyOn(copierService, 'copyText');
-      const button = fixture.debugElement.query(By.css('button')).nativeElement as HTMLButtonElement;
       expect(spy.calls.count()).toBe(0, 'before click');
-      button.click();
+      getButton().click();
       expect(spy.calls.count()).toBe(1, 'after click');
     });
 
     it('should copy code text when clicked', () => {
       const copierService: CopierService = TestBed.get(CopierService);
       const spy = spyOn(copierService, 'copyText');
-      const button = fixture.debugElement.query(By.css('button')).nativeElement as HTMLButtonElement;
+      getButton().click();
-      button.click();
       expect(spy.calls.argsFor(0)[0]).toEqual(oneLineCode, 'after click');
     });
 
@@ -207,8 +226,7 @@ describe('CodeComponent', () => {
       const copierService: CopierService = TestBed.get(CopierService);
       spyOn(snackBar, 'open');
       spyOn(copierService, 'copyText').and.returnValue(true);
-      const button = fixture.debugElement.query(By.css('button')).nativeElement as HTMLButtonElement;
+      getButton().click();
-      button.click();
       expect(snackBar.open).toHaveBeenCalledWith('Code Copied', '', { duration: 800 });
     });
 
@@ -217,8 +235,7 @@ describe('CodeComponent', () => {
       const copierService: CopierService = TestBed.get(CopierService);
       spyOn(snackBar, 'open');
       spyOn(copierService, 'copyText').and.returnValue(false);
-      const button = fixture.debugElement.query(By.css('button')).nativeElement as HTMLButtonElement;
+      getButton().click();
-      button.click();
       expect(snackBar.open).toHaveBeenCalledWith('Copy failed. Please try again!', '', { duration: 800 });
     });
   });
@@ -230,16 +247,18 @@ describe('CodeComponent', () => {
   selector: 'aio-host-comp',
   template: `
       <aio-code md-no-ink [code]="code" [language]="language"
-      [linenums]="linenums" [path]="path" [region]="region" [hideCopy]="hideCopy"></aio-code>
+      [linenums]="linenums" [path]="path" [region]="region"
+      [hideCopy]="hideCopy" [title]="title"></aio-code>
   `
 })
 class HostComponent {
   code = oneLineCode;
+  hideCopy: boolean;
   language: string;
   linenums: boolean | number | string;
   path: string;
   region: string;
-  hideCopy: boolean;
+  title: string;
 }
 
 class TestLogger {

aio/src/app/embedded/code/code.component.ts

@@ -31,19 +31,32 @@ const defaultLineNumsCount = 10; // by default, show linenums over this number
   selector: 'aio-code',
   template: `
     <pre class="prettyprint lang-{{language}}">
-      <button *ngIf="!hideCopy" class="material-icons copy-button" (click)="doCopy()">content_copy</button>
+      <button *ngIf="!hideCopy" class="material-icons copy-button"
+        title="Copy code snippet"
+        [attr.aria-label]="ariaLabel"
+        (click)="doCopy()">
+        <span aria-hidden="true">content_copy</span>
+      </button>
       <code class="animated fadeIn" #codeContainer></code>
     </pre>
     `
 })
 export class CodeComponent implements OnChanges {
 
+  ariaLabel = '';
+
   /**
    * The code to be formatted, this should already be HTML encoded
    */
   @Input()
   code: string;
 
+  /**
+   * set to true if the copy button is not to be shown
+   */
+  @Input()
+  hideCopy: boolean;
+
   /**
    * The language of the code to render
    * (could be javascript, dart, typescript, etc)
@@ -73,10 +86,10 @@ export class CodeComponent implements OnChanges {
   region: string;
 
   /**
-   * set to true if the copy button is not to be shown
+   * title for this snippet (optional)
    */
   @Input()
-  hideCopy: boolean;
+  title: string;
 
   /**
    * The element in the template that will display the formatted code
@@ -91,6 +104,7 @@ export class CodeComponent implements OnChanges {
 
   ngOnChanges() {
     this.code = this.code && leftAlign(this.code);
+    this.ariaLabel = this.title ? `Copy code snippet from ${this.title}` : '';
 
     if (!this.code) {
       const src = this.path ? this.path + (this.region ? '#' + this.region : '') : '';

aio/src/styles/2-modules/_code.scss

@@ -104,7 +104,7 @@ code ol {
   top: 6px;
   right: 8px;
 
-  color: $lightgray;
+  color: $blue-grey-200;
   background-color: transparent;
   border: none;
   cursor: pointer;