Update code to use GET request. Cleanup lint errors & add in basic TypeDocs

src/app/core/xsrf/browser-xsrf.service.spec.ts

@@ -1,8 +1,12 @@
-import { BrowserXSRFService } from './browser-xsrf.service';
 import { HttpClient } from '@angular/common/http';
-import { RESTURLCombiner } from '../url-combiner/rest-url-combiner';
+import {
+  HttpClientTestingModule,
+  HttpTestingController,
+} from '@angular/common/http/testing';
 import { TestBed } from '@angular/core/testing';
-import { HttpClientTestingModule, HttpTestingController } from '@angular/common/http/testing';
+
+import { RESTURLCombiner } from '../url-combiner/rest-url-combiner';
+import { BrowserXSRFService } from './browser-xsrf.service';
 
 describe(`BrowserXSRFService`, () => {
   let service: BrowserXSRFService;
@@ -14,7 +18,7 @@ describe(`BrowserXSRFService`, () => {
   beforeEach(() => {
     TestBed.configureTestingModule({
       imports: [ HttpClientTestingModule ],
-      providers: [ BrowserXSRFService ]
+      providers: [ BrowserXSRFService ],
     });
     httpClient = TestBed.inject(HttpClient);
     httpTestingController = TestBed.inject(HttpTestingController);
@@ -22,20 +26,22 @@ describe(`BrowserXSRFService`, () => {
   });
 
   describe(`initXSRFToken`, () => {
-    it(`should perform a POST to the csrf endpoint`, () => {
+    it(`should perform a GET to the csrf endpoint`, (done: DoneFn) => {
       service.initXSRFToken(httpClient)();
 
       const req = httpTestingController.expectOne({
         url: endpointURL,
-        method: 'POST'
+        method: 'GET',
       });
 
       req.flush({});
       httpTestingController.verify();
+      expect().nothing();
+      done();
     });
 
-    describe(`when the POST succeeds`, () => {
-      it(`should set tokenInitialized$ to true`, () => {
+    describe(`when the GET succeeds`, () => {
+      it(`should set tokenInitialized$ to true`, (done: DoneFn) => {
         service.initXSRFToken(httpClient)();
 
         const req = httpTestingController.expectOne(endpointURL);
@@ -44,19 +50,7 @@ describe(`BrowserXSRFService`, () => {
         httpTestingController.verify();
 
         expect(service.tokenInitialized$.getValue()).toBeTrue();
-      });
-    });
-
-    describe(`when the POST fails`, () => {
-      it(`should set tokenInitialized$ to true`, () => {
-        service.initXSRFToken(httpClient)();
-
-        const req = httpTestingController.expectOne(endpointURL);
-
-        req.error(new ErrorEvent('415'));
-        httpTestingController.verify();
-
-        expect(service.tokenInitialized$.getValue()).toBeTrue();
+        done();
       });
     });
 

src/app/core/xsrf/browser-xsrf.service.ts

@@ -1,21 +1,25 @@
 import { HttpClient } from '@angular/common/http';
 import { Injectable } from '@angular/core';
+import { take } from 'rxjs/operators';
+
 import { RESTURLCombiner } from '../url-combiner/rest-url-combiner';
-import { take, catchError } from 'rxjs/operators';
-import { of as observableOf } from 'rxjs';
 import { XSRFService } from './xsrf.service';
 
+/**
+ * Browser (CSR) Service to obtain a new CSRF/XSRF token when needed by our RequestService
+ * to perform a modify request (e.g. POST/PUT/DELETE).
+ * NOTE: This is primarily necessary before the *first* modifying request, as the CSRF
+ * token may not yet be initialized.
+ */
 @Injectable()
 export class BrowserXSRFService extends XSRFService {
   initXSRFToken(httpClient: HttpClient): () => Promise<any> {
-    return () => new Promise((resolve) => {
-      httpClient.post(new RESTURLCombiner('/security/csrf').toString(), undefined).pipe(
-        // errors are to be expected if the token and the cookie don't match, that's what we're
-        // trying to fix for future requests, so just emit any observable to end up in the
-        // subscribe
-        catchError(() => observableOf(null)),
+    return () => new Promise<void>((resolve) => {
+      // Force a new token to be created by calling the CSRF endpoint
+      httpClient.get(new RESTURLCombiner('/security/csrf').toString(), undefined).pipe(
         take(1),
       ).subscribe(() => {
+        // Once token is returned, set tokenInitialized to true.
         this.tokenInitialized$.next(true);
       });
 

src/app/core/xsrf/server-xsrf.service.spec.ts

@@ -1,6 +1,7 @@
-import { ServerXSRFService } from './server-xsrf.service';
 import { HttpClient } from '@angular/common/http';
 
+import { ServerXSRFService } from './server-xsrf.service';
+
 describe(`ServerXSRFService`, () => {
   let service: ServerXSRFService;
   let httpClient: HttpClient;

src/app/core/xsrf/server-xsrf.service.ts

@@ -1,11 +1,16 @@
 import { HttpClient } from '@angular/common/http';
 import { Injectable } from '@angular/core';
+
 import { XSRFService } from './xsrf.service';
 
+/**
+ * Server (SSR) Service to obtain a new CSRF/XSRF token. Because SSR only triggers GET
+ * requests a CSRF token is never needed.
+ */
 @Injectable()
 export class ServerXSRFService extends XSRFService {
   initXSRFToken(httpClient: HttpClient): () => Promise<any> {
-    return () => new Promise((resolve) => {
+    return () => new Promise<void>((resolve) => {
       // return immediately, and keep tokenInitialized$ false. The server side can make only GET
       // requests, since it can never get a valid XSRF cookie
       resolve();

src/app/core/xsrf/xsrf.service.spec.ts

@@ -1,6 +1,7 @@
-import { XSRFService } from './xsrf.service';
 import { HttpClient } from '@angular/common/http';
 
+import { XSRFService } from './xsrf.service';
+
 class XSRFServiceImpl extends XSRFService {
   initXSRFToken(httpClient: HttpClient): () => Promise<any> {
     return () => null;

src/app/core/xsrf/xsrf.service.ts

@@ -2,6 +2,11 @@ import { HttpClient } from '@angular/common/http';
 import { Injectable } from '@angular/core';
 import { BehaviorSubject } from 'rxjs';
 
+/**
+ * Abstract CSRF/XSRF Service used to track whether a CSRF token has been received
+ * from the DSpace REST API. Once it is received, the "tokenInitialized$" flag will
+ * be set to "true".
+ */
 @Injectable()
 export abstract class XSRFService {
   public tokenInitialized$: BehaviorSubject<boolean> = new BehaviorSubject(false);