feat(aio): add API endpoint for notifying about PR updates

This commit adds an API endpoint for notifying the preview server about PR
updates (`/pr-updated`). According to the update, the preview server can take
several actions. Currently, it will only check and (if necessary) update the
PR's preview visibility (but more actions could be supported in the future).
The API can be used with an automatic trigger (e.g. a GitHub webhook) to
instantly update a PR's preview visibility when it changes.

Fixes #16526

aio/aio-builds-setup/dockerbuild/scripts-js/test/upload-server/upload-server-factory.spec.ts

@@ -442,6 +442,146 @@ describe('uploadServerFactory', () => {
     });
 
 
+    describe('POST /pr-updated', () => {
+      const pr = '9';
+      const url = '/pr-updated';
+      let bvGetPrIsTrustedSpy: jasmine.Spy;
+      let bcUpdatePrVisibilitySpy: jasmine.Spy;
+
+      // Helpers
+      const createRequest = (num: number, action?: string) =>
+        agent.post(url).send({number: num, action});
+
+      beforeEach(() => {
+        bvGetPrIsTrustedSpy = spyOn(buildVerifier, 'getPrIsTrusted');
+        bcUpdatePrVisibilitySpy = spyOn(buildCreator, 'updatePrVisibility');
+      });
+
+
+      it('should respond with 404 for non-POST requests', done => {
+        verifyRequests([
+          agent.get(url).expect(404),
+          agent.put(url).expect(404),
+          agent.patch(url).expect(404),
+          agent.delete(url).expect(404),
+        ], done);
+      });
+
+
+      it('should respond with 400 for requests without a payload', done => {
+        const responseBody = `Missing or empty 'number' field in request: POST ${url} {}`;
+
+        const request1 = agent.post(url);
+        const request2 = agent.post(url).send();
+
+        verifyRequests([
+          request1.expect(400, responseBody),
+          request2.expect(400, responseBody),
+        ], done);
+      });
+
+
+      it('should respond with 400 for requests without a \'number\' field', done => {
+        const responseBodyPrefix = `Missing or empty 'number' field in request: POST ${url}`;
+
+        const request1 = agent.post(url).send({});
+        const request2 = agent.post(url).send({number: null});
+
+        verifyRequests([
+          request1.expect(400, `${responseBodyPrefix} {}`),
+          request2.expect(400, `${responseBodyPrefix} {"number":null}`),
+        ], done);
+      });
+
+
+      it('should call \'BuildVerifier#gtPrIsTrusted()\' with the correct arguments', done => {
+        const req = createRequest(+pr);
+
+        promisifyRequest(req).
+          then(() => expect(bvGetPrIsTrustedSpy).toHaveBeenCalledWith(9)).
+          then(done, done.fail);
+      });
+
+
+      it('should propagate errors from BuildVerifier', done => {
+        bvGetPrIsTrustedSpy.and.callFake(() => Promise.reject('Test'));
+
+        const req = createRequest(+pr).expect(500, 'Test');
+
+        promisifyRequest(req).
+          then(() => {
+            expect(bvGetPrIsTrustedSpy).toHaveBeenCalledWith(9);
+            expect(bcUpdatePrVisibilitySpy).not.toHaveBeenCalled();
+          }).
+          then(done, done.fail);
+      });
+
+
+      it('should call \'BuildCreator#updatePrVisibility()\' with the correct arguments', done => {
+        bvGetPrIsTrustedSpy.and.callFake((pr2: number) => Promise.resolve(pr2 === 42));
+
+        const req1 = createRequest(24);
+        const req2 = createRequest(42);
+
+        Promise.all([
+          promisifyRequest(req1).then(() => expect(bcUpdatePrVisibilitySpy).toHaveBeenCalledWith('24', false)),
+          promisifyRequest(req2).then(() => expect(bcUpdatePrVisibilitySpy).toHaveBeenCalledWith('42', true)),
+        ]).then(done, done.fail);
+      });
+
+
+      it('should propagate errors from BuildCreator', done => {
+        bcUpdatePrVisibilitySpy.and.callFake(() => Promise.reject('Test'));
+
+        const req = createRequest(+pr).expect(500, 'Test');
+        verifyRequests([req], done);
+      });
+
+
+      describe('on success', () => {
+
+        it('should respond with 200 (action: undefined)', done => {
+          bvGetPrIsTrustedSpy.and.returnValues(Promise.resolve(true), Promise.resolve(false));
+
+          const reqs = [4, 2].map(num => createRequest(num).expect(200, http.STATUS_CODES[200]));
+          verifyRequests(reqs, done);
+        });
+
+
+        it('should respond with 200 (action: labeled)', done => {
+          bvGetPrIsTrustedSpy.and.returnValues(Promise.resolve(true), Promise.resolve(false));
+
+          const reqs = [4, 2].map(num => createRequest(num, 'labeled').expect(200, http.STATUS_CODES[200]));
+          verifyRequests(reqs, done);
+        });
+
+
+        it('should respond with 200 (action: unlabeled)', done => {
+          bvGetPrIsTrustedSpy.and.returnValues(Promise.resolve(true), Promise.resolve(false));
+
+          const reqs = [4, 2].map(num => createRequest(num, 'unlabeled').expect(200, http.STATUS_CODES[200]));
+          verifyRequests(reqs, done);
+        });
+
+
+        it('should respond with 200 (and do nothing) if \'action\' implies no visibility change', done => {
+          const promises = ['foo', 'notlabeled'].
+            map(action => createRequest(+pr, action).expect(200, http.STATUS_CODES[200])).
+            map(promisifyRequest);
+
+          Promise.all(promises).
+            then(() => {
+              expect(bvGetPrIsTrustedSpy).not.toHaveBeenCalled();
+              expect(bcUpdatePrVisibilitySpy).not.toHaveBeenCalled();
+            }).
+            then(done, done.fail);
+        });
+
+      });
+
+    });
+
+
     describe('ALL *', () => {
 
       it('should respond with 404', done => {