feat(aio): add LocationService.path() method (#16139)

This enables things like embedded components easy access to a clean version
of the current location path.

aio/src/app/shared/location.service.spec.ts

@@ -124,6 +124,37 @@ describe('LocationService', () => {
     });
   });
 
+  describe('path', () => {
+    it('should ask Location for the current path without the hash', () => {
+      const location: MockLocationStrategy = injector.get(LocationStrategy);
+      const service: LocationService = injector.get(LocationService);
+
+      // We cannot test this directly in the following test because the `MockLocationStrategy`
+      // does not remove the hash from the path, even if we do pass `false`.
+
+      spyOn(location, 'path').and.callThrough();
+      service.path();
+      expect(location.path).toHaveBeenCalledWith(false);
+    });
+
+    it('should return the current location.path, with the query and trailing slash stripped off', () => {
+      const location: MockLocationStrategy = injector.get(LocationStrategy);
+      const service: LocationService = injector.get(LocationService);
+
+      location.simulatePopState('a/b/c?foo=bar&moo=car');
+      expect(service.path()).toEqual('a/b/c');
+
+      location.simulatePopState('c/d/e');
+      expect(service.path()).toEqual('c/d/e');
+
+      location.simulatePopState('a/b/c/?foo=bar&moo=car');
+      expect(service.path()).toEqual('a/b/c');
+
+      location.simulatePopState('c/d/e/');
+      expect(service.path()).toEqual('c/d/e');
+    });
+  });
+
   describe('search', () => {
     it('should read the query from the current location.path', () => {
       const location: MockLocationStrategy = injector.get(LocationStrategy);

aio/src/app/shared/location.service.ts

@@ -42,6 +42,16 @@ export class LocationService {
     return url.replace(/^\/+/, '');
   }
 
+  /**
+   * Get the current path, without trailing slash, hash fragment or query params
+   */
+  path(): string {
+    let path = this.location.path(false);
+    path = path.match(/[^?]*/)[0]; // strip off query
+    path = path.replace(/\/$/, ''); // strip off trailing slash
+    return path;
+  }
+
   search(): { [index: string]: string; } {
     const search = {};
     const path = this.location.path();

aio/src/testing/location.service.ts

@@ -7,6 +7,8 @@ export class MockLocationService {
   setSearch = jasmine.createSpy('setSearch');
   go = jasmine.createSpy('Location.go').and
               .callFake((url: string) => this.urlSubject.next(url));
+  path = jasmine.createSpy('Location.path').and
+              .callFake(() => this.urlSubject.getValue().split('?')[0]);
   handleAnchorClick = jasmine.createSpy('Location.handleAnchorClick')
       .and.returnValue(false); // prevent click from causing a browser navigation