fix(common): accept falsy values as HTTP bodies (#19958)

Previously, HttpClient used the overly clever test "body || null"
to determine when a body parameter was provided. This breaks when
the valid bodies '0' or 'false' are provided.

This change tests directly against 'undefined' to detect the presence
of the body parameter, and thus correctly allows falsy values through.

Fixes #19825.
Fixes #19195.

PR Close #19958

packages/common/http/src/client.ts

@@ -371,7 +371,7 @@ export class HttpClient {
       }
 
       // Construct the request.
-      req = new HttpRequest(first, url !, options.body || null, {
+      req = new HttpRequest(first, url !, (options.body !== undefined ? options.body : null), {
         headers,
         params,
         reportProgress: options.reportProgress,

packages/common/http/src/request.ts

@@ -171,7 +171,7 @@ export class HttpRequest<T> {
     // the body argument is to use a known no-body method like GET.
     if (mightHaveBody(this.method) || !!fourth) {
       // Body is the third argument, options are the fourth.
-      this.body = third as T || null;
+      this.body = (third !== undefined) ? third as T : null;
       options = fourth;
     } else {
       // No body required, options are the third argument. The body stays null.

packages/common/http/src/response.ts

@@ -262,7 +262,7 @@ export class HttpResponse<T> extends HttpResponseBase {
     body?: T | null, headers?: HttpHeaders; status?: number; statusText?: string; url?: string;
   } = {}) {
     super(init);
-    this.body = init.body || null;
+    this.body = init.body !== undefined ? init.body : null;
   }
 
   readonly type: HttpEventType.Response = HttpEventType.Response;

packages/common/http/test/client_spec.ts

@@ -115,6 +115,26 @@ export function main() {
         expect(testReq.request.body).toBe(body);
         testReq.flush('hello world');
       });
+      it('with a json body of false', (done: DoneFn) => {
+        client.post('/test', false, {observe: 'response', responseType: 'text'}).subscribe(res => {
+          expect(res.ok).toBeTruthy();
+          expect(res.status).toBe(200);
+          done();
+        });
+        const testReq = backend.expectOne('/test');
+        expect(testReq.request.body).toBe(false);
+        testReq.flush('hello world');
+      });
+      it('with a json body of 0', (done: DoneFn) => {
+        client.post('/test', 0, {observe: 'response', responseType: 'text'}).subscribe(res => {
+          expect(res.ok).toBeTruthy();
+          expect(res.status).toBe(200);
+          done();
+        });
+        const testReq = backend.expectOne('/test');
+        expect(testReq.request.body).toBe(0);
+        testReq.flush('hello world');
+      });
       it('with an arraybuffer', (done: DoneFn) => {
         const body = new ArrayBuffer(4);
         client.post('/test', body, {observe: 'response', responseType: 'text'}).subscribe(res => {

packages/common/http/test/response_spec.ts

@@ -40,6 +40,10 @@ export function main() {
         expect(resp.ok).toBeTruthy();
         expect(resp.url).toBeNull();
       });
+      it('accepts a falsy body', () => {
+        expect(new HttpResponse({body: false}).body).toEqual(false);
+        expect(new HttpResponse({body: 0}).body).toEqual(0);
+      });
     });
     it('.ok is determined by status', () => {
       const good = new HttpResponse({status: 200});