[appveyor] Error handling in BaseService (#1590)

Make a clear distinction between programmer errors ("internal errors") and runtime errors, and allow configuring the server to let the programmer errors bubble up in development and unit testing. This saves a huge amount of time because it generates ordinary stack traces when things go wrong. And, if these errors occur in production, we'll catch them, and display **shields | internal error** which is the equivalent of a 500 error.

services/appveyor/appveyor.js

@@ -1,26 +1,23 @@
 'use strict';
 
 const BaseService = require('../base');
+const {
+  checkErrorResponse,
+  asJson,
+} = require('../../lib/error-helper');
 
-/**
- * AppVeyor CI integration.
- */
 module.exports = class AppVeyor extends BaseService {
   async handle({repo, branch}) {
     let apiUrl = 'https://ci.appveyor.com/api/projects/' + repo;
     if (branch != null) {
       apiUrl += '/branch/' + branch;
     }
-    const {buffer, res} = await this._sendAndCacheRequest(apiUrl, {
+    const json = await this._sendAndCacheRequest(apiUrl, {
       headers: { 'Accept': 'application/json' }
-    });
+    }).then(checkErrorResponse.asPromise({ notFoundMessage: 'project not found or access denied' }))
+      .then(asJson);
 
-    if (res.statusCode === 404) {
-      return {message: 'project not found or access denied'};
-    }
-
-    const data = JSON.parse(buffer);
-    const status = data.build.status;
+    const { build: { status } } = json;
     if (status === 'success') {
       return {message: 'passing', color: 'brightgreen'};
     } else if (status !== 'running' && status !== 'queued') {

services/appveyor/appveyor.tester.js

@@ -25,6 +25,11 @@ t.create('CI 404')
 .get('/ci/somerandomproject/thatdoesntexits.json')
   .expectJSON({ name: 'build', value: 'project not found or access denied' });
 
+t.create('CI (connection error)')
+  .get('/ci/this-one/is-not-real-either.json')
+  .networkOff()
+  .expectJSON({ name: 'build', value: 'inaccessible' });
+
 // Test AppVeyor tests status badge
 t.create('tests status')
   .get('/tests/NZSmartie/coap-net-iu0to.json')