refactor(maven): Simplify downloadHttpProtocol return type

lib/modules/datasource/maven/index.ts

@@ -145,19 +145,24 @@ export class MavenDatasource extends Datasource {
       try {
         const indexUrl = getMavenUrl(dependency, repoUrl, 'index.html');
         const res = await downloadHttpProtocol(this.http, indexUrl);
-        const { body = '' } = res;
-        for (const line of body.split(newlineRegex)) {
-          const match = line.trim().match(mavenCentralHtmlVersionRegex);
-          if (match) {
-            const { version, releaseTimestamp: timestamp } =
-              match?.groups ?? /* istanbul ignore next: hard to test */ {};
-            if (version && timestamp) {
-              const date = DateTime.fromFormat(timestamp, 'yyyy-MM-dd HH:mm', {
-                zone: 'UTC',
-              });
-              if (date.isValid) {
-                const releaseTimestamp = date.toISO();
-                workingReleaseMap[version] = { version, releaseTimestamp };
+        if (res) {
+          for (const line of res.body.split(newlineRegex)) {
+            const match = line.trim().match(mavenCentralHtmlVersionRegex);
+            if (match) {
+              const { version, releaseTimestamp: timestamp } =
+                match?.groups ?? /* istanbul ignore next: hard to test */ {};
+              if (version && timestamp) {
+                const date = DateTime.fromFormat(
+                  timestamp,
+                  'yyyy-MM-dd HH:mm',
+                  {
+                    zone: 'UTC',
+                  },
+                );
+                if (date.isValid) {
+                  const releaseTimestamp = date.toISO();
+                  workingReleaseMap[version] = { version, releaseTimestamp };
+                }
               }
             }
           }

lib/modules/datasource/maven/util.spec.ts

@@ -1,6 +1,7 @@
+import type Request from 'got/dist/source/core';
 import { partial } from '../../../../test/util';
 import { HOST_DISABLED } from '../../../constants/error-messages';
-import type { Http } from '../../../util/http';
+import { type Http, HttpError } from '../../../util/http';
 import { parseUrl } from '../../../util/url';
 import {
   checkResource,
@@ -9,6 +10,38 @@ import {
   downloadS3Protocol,
 } from './util';
 
+function httpError({
+  name,
+  message = 'unknown error',
+  code,
+  request = {},
+  response,
+}: {
+  name?: string;
+  message?: string;
+  code?: HttpError['code'];
+  request?: Partial<Request>;
+  response?: Partial<Response>;
+}): HttpError {
+  type Writeable<T> = { -readonly [P in keyof T]: T[P] };
+
+  const err = new HttpError(
+    message,
+    { code },
+    request as never,
+  ) as Writeable<HttpError>;
+
+  if (name) {
+    err.name = name;
+  }
+
+  if (response) {
+    err.response = response as never;
+  }
+
+  return err;
+}
+
 describe('modules/datasource/maven/util', () => {
   describe('downloadMavenXml', () => {
     it('returns empty object for unsupported protocols', async () => {
@@ -39,51 +72,43 @@ describe('modules/datasource/maven/util', () => {
   describe('downloadHttpProtocol', () => {
     it('returns empty for HOST_DISABLED error', async () => {
       const http = partial<Http>({
-        get: () =>
-          Promise.reject(
-            Object.assign(new Error(), { message: HOST_DISABLED }),
-          ),
+        get: () => Promise.reject(httpError({ message: HOST_DISABLED })),
       });
       const res = await downloadHttpProtocol(http, 'some://');
-      expect(res).toStrictEqual({});
+      expect(res).toBeNull();
     });
 
     it('returns empty for host error', async () => {
       const http = partial<Http>({
-        get: () =>
-          Promise.reject(Object.assign(new Error(), { code: 'ETIMEDOUT' })),
+        get: () => Promise.reject(httpError({ code: 'ETIMEDOUT' })),
       });
       const res = await downloadHttpProtocol(http, 'some://');
-      expect(res).toStrictEqual({});
+      expect(res).toBeNull();
     });
 
-    it('returns empty for temporal error', async () => {
+    it('returns empty for temporary error', async () => {
       const http = partial<Http>({
-        get: () =>
-          Promise.reject(Object.assign(new Error(), { code: 'ECONNRESET' })),
+        get: () => Promise.reject(httpError({ code: 'ECONNRESET' })),
       });
       const res = await downloadHttpProtocol(http, 'some://');
-      expect(res).toStrictEqual({});
+      expect(res).toBeNull();
     });
 
     it('returns empty for connection error', async () => {
       const http = partial<Http>({
-        get: () =>
-          Promise.reject(Object.assign(new Error(), { code: 'ECONNREFUSED' })),
+        get: () => Promise.reject(httpError({ code: 'ECONNREFUSED' })),
       });
       const res = await downloadHttpProtocol(http, 'some://');
-      expect(res).toStrictEqual({});
+      expect(res).toBeNull();
     });
 
     it('returns empty for unsupported error', async () => {
       const http = partial<Http>({
         get: () =>
-          Promise.reject(
-            Object.assign(new Error(), { name: 'UnsupportedProtocolError' }),
-          ),
+          Promise.reject(httpError({ name: 'UnsupportedProtocolError' })),
       });
       const res = await downloadHttpProtocol(http, 'some://');
-      expect(res).toStrictEqual({});
+      expect(res).toBeNull();
     });
   });