fix(web-server): Ensure filesPromise is always resolvable

Closes #1544

lib/file-list.js

@@ -221,14 +221,14 @@ Object.defineProperty(List.prototype, 'files', {
       return pattern.served
     })
     .map(function (p) {
-      return from(self.buckets.get(p.pattern)).sort(byPath)
+      return from(self.buckets.get(p.pattern) || []).sort(byPath)
     })
 
     var included = this._patterns.filter(function (pattern) {
       return pattern.included
     })
     .map(function (p) {
-      return from(self.buckets.get(p.pattern)).sort(byPath)
+      return from(self.buckets.get(p.pattern) || []).sort(byPath)
     })
 
     var uniqFlat = function (list) {

lib/middleware/common.js

@@ -9,7 +9,7 @@ var PromiseContainer = function () {
   var promise
 
   this.then = function (success, error) {
-    return promise.then(success, error)
+    return promise.then(success).catch(error)
   }
 
   this.set = function (newPromise) {

lib/web-server.js

@@ -29,12 +29,16 @@ var createCustomHandler = function (customFileHandlers, /* config.basePath */ ba
 
 createCustomHandler.$inject = ['customFileHandlers', 'config.basePath']
 
-var createWebServer = function (injector, emitter) {
+var createWebServer = function (injector, emitter, fileList) {
   var config = injector.get('config')
   var serveStaticFile = common.createServeFile(fs, path.normalize(__dirname + '/../static'))
   var serveFile = common.createServeFile(fs)
   var filesPromise = new common.PromiseContainer()
 
+  // Set an empty list of files to avoid race issues with
+  // file_list_modified not having been emitted yet
+  filesPromise.set(Promise.resolve(fileList.files))
+
   emitter.on('file_list_modified', function (files) {
     filesPromise.set(Promise.resolve(files))
   })

test/unit/web-server.spec.js

@@ -47,7 +47,7 @@ describe('web-server', () => {
         config: ['value', {basePath: '/base/path', urlRoot: '/'}],
         customFileHandlers: ['value', customFileHandlers],
         emitter: ['value', emitter],
-        fileList: ['value', null],
+        fileList: ['value', {files: {served: [], included: []}}],
         capturedBrowsers: ['value', null],
         reporter: ['value', null],
         executor: ['value', null],
@@ -82,6 +82,19 @@ describe('web-server', () => {
         .expect(200, 'new-js-source')
     })
 
+    it('should serve no files when they are not available yet', () => {
+      return request(server)
+        .get('/base/new.js')
+        .expect(404)
+        .then(() => {
+          servedFiles(new Set([new File('/base/path/new.js')]))
+
+          return request(server)
+            .get('/base/new.js')
+            .expect(200, 'new-js-source')
+        })
+    })
+
     it('should load custom handlers', () => {
       servedFiles(new Set())
 
@@ -125,7 +138,7 @@ describe('web-server', () => {
         config: ['value', {basePath: '/base/path', urlRoot: '/', protocol: 'https:', httpsServerOptions: credentials}],
         customFileHandlers: ['value', customFileHandlers],
         emitter: ['value', emitter],
-        fileList: ['value', null],
+        fileList: ['value', {files: {served: [], included: []}}],
         capturedBrowsers: ['value', null],
         reporter: ['value', null],
         executor: ['value', null],