chore(cli): some errors are not being caught when fetching notices (#…

…19112)

This PR handles two additional error scenarios:

1. When there is an error in the _request_. An example is DNS name resolution.
2. When `https.get` itself throws an error instead of sending the error to a registered callback function. This one is unlikely to happen (the only thing I've found that would cause this is failure to parse the URL), but I'm just taking the opportunity to close all the gaps.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/aws-cdk/lib/notices.ts

@@ -106,31 +106,40 @@ export interface NoticeDataSource {
 export class WebsiteNoticeDataSource implements NoticeDataSource {
   fetch(): Promise<Notice[]> {
     return new Promise((resolve) => {
-      https.get('https://cli.cdk.dev-tools.aws.dev/notices.json', res => {
-        if (res.statusCode === 200) {
-          res.setEncoding('utf8');
-          let rawData = '';
-          res.on('data', (chunk) => {
-            rawData += chunk;
-          });
-          res.on('end', () => {
-            try {
-              const data = JSON.parse(rawData).notices as Notice[];
-              resolve(data ?? []);
-            } catch (e) {
-              debug(`Failed to parse notices: ${e}`);
+      try {
+        const req = https.get('https://cli.cdk.dev-tools.aws.dev/notices.json', res => {
+          if (res.statusCode === 200) {
+            res.setEncoding('utf8');
+            let rawData = '';
+            res.on('data', (chunk) => {
+              rawData += chunk;
+            });
+            res.on('end', () => {
+              try {
+                const data = JSON.parse(rawData).notices as Notice[];
+                resolve(data ?? []);
+              } catch (e) {
+                debug(`Failed to parse notices: ${e}`);
+                resolve([]);
+              }
+            });
+            res.on('error', e => {
+              debug(`Failed to fetch notices: ${e}`);
               resolve([]);
-            }
-          });
-          res.on('error', e => {
-            debug(`Failed to fetch notices: ${e}`);
+            });
+          } else {
+            debug(`Failed to fetch notices. Status code: ${res.statusCode}`);
             resolve([]);
-          });
-        } else {
-          debug(`Failed to fetch notices. Status code: ${res.statusCode}`);
+          }
+        });
+        req.on('error', e => {
+          debug(`Error on request: ${e}`);
           resolve([]);
-        }
-      });
+        });
+      } catch (e) {
+        debug(`HTTPS 'get' call threw an error: ${e}`);
+        resolve([]);
+      }
     });
   }
 }

packages/aws-cdk/test/notices.test.ts

@@ -1,3 +1,4 @@
+import * as https from 'https';
 import * as os from 'os';
 import * as path from 'path';
 import * as fs from 'fs-extra';
@@ -211,6 +212,27 @@ describe('cli notices', () => {
       expect(result).toEqual([]);
     });
 
+    test('returns empty array when HTTPS call throws', async () => {
+      const mockGet = jest.spyOn(https, 'get')
+        .mockImplementation(() => { throw new Error('No connection'); });
+
+      const result = await dataSource.fetch();
+
+      expect(result).toEqual([]);
+
+      mockGet.mockRestore();
+    });
+
+    test('returns empty array when the request has an error', async () => {
+      nock('https://cli.cdk.dev-tools.aws.dev')
+        .get('/notices.json')
+        .replyWithError('DNS resolution failed');
+
+      const result = await dataSource.fetch();
+
+      expect(result).toEqual([]);
+    });
+
     function mockCall(statusCode: number, body: any): Promise<Notice[]> {
       nock('https://cli.cdk.dev-tools.aws.dev')
         .get('/notices.json')