improve thumbnailcomponent test coverage

src/app/thumbnail/thumbnail.component.spec.ts

@@ -4,7 +4,7 @@ import { By } from '@angular/platform-browser';
 import { Bitstream } from '../core/shared/bitstream.model';
 import { SafeUrlPipe } from '../shared/utils/safe-url-pipe';
 
-import { ThumbnailComponent } from './thumbnail.component';
+import { THUMBNAIL_PLACEHOLDER, ThumbnailComponent } from './thumbnail.component';
 
 describe('ThumbnailComponent', () => {
   let comp: ThumbnailComponent;
@@ -25,26 +25,40 @@ describe('ThumbnailComponent', () => {
     el = de.nativeElement;
   });
 
-  it('should display image', () => {
-    const thumbnail = new Bitstream();
-    thumbnail._links = {
-      self: { href: 'self.url' },
-      bundle: { href: 'bundle.url' },
-      format: { href: 'format.url' },
-      content: { href: 'content.url' },
-    };
-    comp.thumbnail = thumbnail;
-    fixture.detectChanges();
-    const image: HTMLElement = de.query(By.css('img')).nativeElement;
-    expect(image.getAttribute('src')).toBe(comp.thumbnail._links.content.href);
+  describe('when the thumbnail exists', () => {
+    it('should display an image', () => {
+      const thumbnail = new Bitstream();
+      thumbnail._links = {
+        self: { href: 'self.url' },
+        bundle: { href: 'bundle.url' },
+        format: { href: 'format.url' },
+        content: { href: 'content.url' },
+      };
+      comp.thumbnail = thumbnail;
+      fixture.detectChanges();
+      const image: HTMLElement = de.query(By.css('img')).nativeElement;
+      expect(image.getAttribute('src')).toBe(comp.thumbnail._links.content.href);
+    });
   });
-
-  it('should display placeholder', () => {
-    const thumbnail = new Bitstream();
-    comp.thumbnail = thumbnail;
-    fixture.detectChanges();
-    const image: HTMLElement = de.query(By.css('img')).nativeElement;
-    expect(image.getAttribute('src')).toBe(comp.defaultImage);
+  describe(`when the thumbnail doesn't exist`, () => {
+    describe('and there is a default image', () => {
+      it('should display the default image', () => {
+        comp.src = 'http://bit.stream';
+        comp.defaultImage = 'http://default.img';
+        comp.errorHandler();
+        expect(comp.src).toBe(comp.defaultImage);
+      });
+    });
+    describe('and there is no default image', () => {
+      it('should display the placeholder', () => {
+        comp.src = 'http://default.img';
+        comp.defaultImage = 'http://default.img';
+        comp.errorHandler();
+        expect(comp.src).toBe(THUMBNAIL_PLACEHOLDER);
+      })
+    });
   });
 
+;
+
 });

src/app/thumbnail/thumbnail.component.ts

@@ -5,7 +5,7 @@ import { hasValue } from '../shared/empty.util';
 /**
  * A fallback placeholder image as a base64 string
  */
-const placeholder = 'data:image/svg+xml;charset=UTF-8,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2293%22%20height%3D%22120%22%20viewBox%3D%220%200%2093%20120%22%20preserveAspectRatio%3D%22none%22%3E%3C!--%0ASource%20URL%3A%20holder.js%2F93x120%3Ftext%3DNo%20Thumbnail%0ACreated%20with%20Holder.js%202.8.2.%0ALearn%20more%20at%20http%3A%2F%2Fholderjs.com%0A(c)%202012-2015%20Ivan%20Malopinsky%20-%20http%3A%2F%2Fimsky.co%0A--%3E%3Cdefs%3E%3Cstyle%20type%3D%22text%2Fcss%22%3E%3C!%5BCDATA%5B%23holder_1543e460b05%20text%20%7B%20fill%3A%23AAAAAA%3Bfont-weight%3Abold%3Bfont-family%3AArial%2C%20Helvetica%2C%20Open%20Sans%2C%20sans-serif%2C%20monospace%3Bfont-size%3A10pt%20%7D%20%5D%5D%3E%3C%2Fstyle%3E%3C%2Fdefs%3E%3Cg%20id%3D%22holder_1543e460b05%22%3E%3Crect%20width%3D%2293%22%20height%3D%22120%22%20fill%3D%22%23FFFFFF%22%2F%3E%3Cg%3E%3Ctext%20x%3D%2235.6171875%22%20y%3D%2257%22%3ENo%3C%2Ftext%3E%3Ctext%20x%3D%2210.8125%22%20y%3D%2272%22%3EThumbnail%3C%2Ftext%3E%3C%2Fg%3E%3C%2Fg%3E%3C%2Fsvg%3E';
+export const THUMBNAIL_PLACEHOLDER = 'data:image/svg+xml;charset=UTF-8,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2293%22%20height%3D%22120%22%20viewBox%3D%220%200%2093%20120%22%20preserveAspectRatio%3D%22none%22%3E%3C!--%0ASource%20URL%3A%20holder.js%2F93x120%3Ftext%3DNo%20Thumbnail%0ACreated%20with%20Holder.js%202.8.2.%0ALearn%20more%20at%20http%3A%2F%2Fholderjs.com%0A(c)%202012-2015%20Ivan%20Malopinsky%20-%20http%3A%2F%2Fimsky.co%0A--%3E%3Cdefs%3E%3Cstyle%20type%3D%22text%2Fcss%22%3E%3C!%5BCDATA%5B%23holder_1543e460b05%20text%20%7B%20fill%3A%23AAAAAA%3Bfont-weight%3Abold%3Bfont-family%3AArial%2C%20Helvetica%2C%20Open%20Sans%2C%20sans-serif%2C%20monospace%3Bfont-size%3A10pt%20%7D%20%5D%5D%3E%3C%2Fstyle%3E%3C%2Fdefs%3E%3Cg%20id%3D%22holder_1543e460b05%22%3E%3Crect%20width%3D%2293%22%20height%3D%22120%22%20fill%3D%22%23FFFFFF%22%2F%3E%3Cg%3E%3Ctext%20x%3D%2235.6171875%22%20y%3D%2257%22%3ENo%3C%2Ftext%3E%3Ctext%20x%3D%2210.8125%22%20y%3D%2272%22%3EThumbnail%3C%2Ftext%3E%3C%2Fg%3E%3C%2Fg%3E%3C%2Fsvg%3E';
 
 /**
  * This component renders a given Bitstream as a thumbnail.
@@ -27,7 +27,7 @@ export class ThumbnailComponent implements OnInit {
   /**
    * The default image, used if the thumbnail isn't set or can't be downloaded
    */
-  @Input() defaultImage? = placeholder;
+  @Input() defaultImage? = THUMBNAIL_PLACEHOLDER;
 
   /**
    * The src attribute used in the template to render the image.
@@ -51,11 +51,11 @@ export class ThumbnailComponent implements OnInit {
    * If the image can't be found, use the defaultImage instead.
    * If that also can't be found, use the base64 placeholder.
    */
-  errorHandler(event) {
-    if (event.currentTarget.src !== this.defaultImage) {
-      event.currentTarget.src = this.defaultImage;
+  errorHandler() {
+    if (this.src !== this.defaultImage) {
+      this.src = this.defaultImage;
     } else {
-      event.currentTarget.src = placeholder;
+      this.src = THUMBNAIL_PLACEHOLDER;
     }
   }
 }