fix(e2e): screenshot changes will display proper error message

closes #191
closes #192

Closes #194

Author: Robert Messerle

e2e/_screenshot.js

@@ -58,14 +58,14 @@ class Screenshot {
       let referenceScreenshot = mapnik.Image.open(this.path);
       this.overwriteExistingScreenshot();
       if (referenceScreenshot.compare(this.png)) {
-        throw new Error(`screenshot "${this.id}" has changed.`);
+        throw `screenshot "${this.id}" has changed.`;
       } else {
         console.info('[STATUS] Screenshot has not changed');
       }
     } catch (e) {
-      console.info(`[STATUS] No reference screenshot found`);
+      console.error(`[ERROR] `, e);
       this.overwriteExistingScreenshot();
-      throw new Error(`screenshot "${this.id}" was not found.`);
+      throw e;
     }
   }
 

e2e/index.e2e.js

@@ -5,7 +5,7 @@ describe('hello, protractor', function () {
     browser.get('/');
     it('should have a title', function () {
       expect(browser.getTitle()).toBe('Material2');
-      screenshot('initial state');
+      screenshot('demo page: index');
     });
   });
 });