feat(UnsubscriptionError): add messages from inner errors to output m…

…essage

- Adds improved console logging behavior

closes #1590

spec/util/UnsubscriptionError-spec.ts

@@ -0,0 +1,28 @@
+import {expect} from 'chai';
+import * as Rx from '../../dist/cjs/Rx';
+
+const { Observable, UnsubscriptionError } = Rx;
+
+/** @test {UnsubscriptionError} */
+describe('UnsubscriptionError', () => {
+  it('should create a message that is a clear indication of its internal errors', () => {
+    const err1 = new Error('Swiss cheese tastes amazing but smells like socks');
+    const err2 = new Error('User too big to fit in tiny European elevator');
+    const source1 = Observable.create(() => () => { throw err1; });
+    const source2 = Observable.timer(1000);
+    const source3 = Observable.create(() => () => { throw err2; });
+    const source = source1.merge(source2, source3);
+
+    const subscription = source.subscribe();
+
+    try {
+      subscription.unsubscribe();
+    } catch (err) {
+      expect(err instanceof UnsubscriptionError).to.equal(true);
+      expect(err.message).to.equal(`2 errors occurred during unsubscription:
+1) ${err1}
+2) ${err2}`);
+      expect(err.name).to.equal('UnsubscriptionError');
+    }
+  });
+});

src/util/UnsubscriptionError.ts

@@ -4,7 +4,9 @@
  */
 export class UnsubscriptionError extends Error {
   constructor(public errors: any[]) {
-    super('unsubscriptoin error(s)');
+    super();
     this.name = 'UnsubscriptionError';
+    this.message = errors ? `${errors.length} errors occurred during unsubscription:
+${errors.map((err, i) => `${i + 1}) ${err.toString()}`).join('\n')}` : '';
   }
 }