fix an issue where the current page would be used instead of a third party referrer

Author: artlowel

src/app/core/services/browser.referrer.service.spec.ts

@@ -10,7 +10,7 @@ describe(`BrowserReferrerService`, () => {
 
   beforeEach(() => {
     routeService = {
-      getPreviousUrl: () => observableOf('')
+      getHistory: () => observableOf([])
     } as any;
     service = new BrowserReferrerService(
       { referrer: documentReferrer },
@@ -20,12 +20,22 @@ describe(`BrowserReferrerService`, () => {
   });
 
   describe(`getReferrer`, () => {
-    let prevUrl: string;
+    describe(`when the history is an empty`, () => {
+      beforeEach(() => {
+        spyOn(routeService, 'getHistory').and.returnValue(observableOf([]));
+      });
+
+      it(`should return document.referrer`, (done: DoneFn) => {
+        service.getReferrer().subscribe((emittedReferrer: string) => {
+          expect(emittedReferrer).toBe(documentReferrer);
+          done();
+        });
+      });
+    });
 
-    describe(`when getPreviousUrl is an empty string`, () => {
+    describe(`when the history only contains the current route`, () => {
       beforeEach(() => {
-        prevUrl = '';
-        spyOn(routeService, 'getPreviousUrl').and.returnValue(observableOf(prevUrl));
+        spyOn(routeService, 'getHistory').and.returnValue(observableOf(['/current/route']));
       });
 
       it(`should return document.referrer`, (done: DoneFn) => {
@@ -36,13 +46,18 @@ describe(`BrowserReferrerService`, () => {
       });
     });
 
-    describe(`when getPreviousUrl is not empty`, () => {
+    describe(`when the history contains multiple routes`, () => {
+      const prevUrl = '/the/route/we/need';
       beforeEach(() => {
-        prevUrl = '/some/local/route';
-        spyOn(routeService, 'getPreviousUrl').and.returnValue(observableOf(prevUrl));
+        spyOn(routeService, 'getHistory').and.returnValue(observableOf([
+          '/first/route',
+          '/second/route',
+          prevUrl,
+          '/current/route'
+        ]));
       });
 
-      it(`should return the value emitted by getPreviousUrl combined with the origin from HardRedirectService`, (done: DoneFn) => {
+      it(`should return the last route before the current one combined with the origin from HardRedirectService`, (done: DoneFn) => {
         service.getReferrer().subscribe((emittedReferrer: string) => {
           expect(emittedReferrer).toBe(origin + prevUrl);
           done();

src/app/core/services/browser.referrer.service.ts

@@ -1,7 +1,7 @@
 import { ReferrerService } from './referrer.service';
 import { Observable } from 'rxjs';
 import { map } from 'rxjs/operators';
-import { isEmpty } from '../../shared/empty.util';
+import { isEmpty, hasNoValue } from '../../shared/empty.util';
 import { URLCombiner } from '../url-combiner/url-combiner';
 import { Inject, Injectable } from '@angular/core';
 import { DOCUMENT } from '@angular/common';
@@ -33,13 +33,19 @@ export class BrowserReferrerService extends ReferrerService {
    * in the store yet, document.referrer will be used
    */
   public getReferrer(): Observable<string> {
-    return this.routeService.getPreviousUrl().pipe(
-      map((prevUrl: string) => {
-        // if we don't have anything in the history yet, return document.referrer
-        // (note that that may be empty too, e.g. if you've just opened a new browser tab)
-        if (isEmpty(prevUrl)) {
+    return this.routeService.getHistory().pipe(
+      map((history: string[]) => {
+        const currentURL = history[history.length - 1];
+        // if the current URL isn't set yet, or the only URL in the history is the current one,
+        // return document.referrer (note that that may be empty too, e.g. if you've just opened a
+        // new browser tab)
+        if (hasNoValue(currentURL) || history.every((url: string) => url === currentURL)) {
           return this.document.referrer;
         } else {
+          // reverse the history
+          const reversedHistory = [...history].reverse();
+          // and find the first URL that differs from the current one
+          const prevUrl = reversedHistory.find((url: string) => url !== currentURL);
           return new URLCombiner(this.hardRedirectService.getCurrentOrigin(), prevUrl).toString();
         }
       })