add async mock capability.. fixes #26

example/mock-async/.local-web-server.json

@@ -0,0 +1,8 @@
+{
+  "mocks": [
+    {
+      "route": "/",
+      "module": "/mocks/delayed.js"
+    }
+  ]
+}

example/mock-async/mocks/delayed.js

@@ -0,0 +1,10 @@
+module.exports = {
+  response: function (ctx) {
+    return new Promise((resolve, reject) => {
+      setTimeout(() => {
+        ctx.body = `<h1>You waited 2s for this</h1>`
+        resolve()
+      }, 2000)
+    })
+  }
+}

lib/middleware.js

@@ -101,10 +101,9 @@ function mockResponses (route, targets) {
       }
 
       if (target) {
-        // debug('target response: %s', target.response)
         if (t.isFunction(target.response)) {
           const pathMatches = ctx.path.match(pathRe).slice(1)
-          target.response.apply(null, [ctx].concat(pathMatches))
+          return target.response.apply(null, [ctx].concat(pathMatches)) 
         } else if (t.isPlainObject(target.response)) {
           Object.assign(ctx.response, target.response)
         } else {

test/test.js

@@ -335,3 +335,31 @@ test('mock: response function args', function (t) {
       .then(server.close.bind(server))
   })
 })
+
+test('mock: async response function', function (t) {
+  t.plan(2)
+  const app = localWebServer({
+    log: { format: 'none' },
+    mocks: [
+      {
+        route: '/test',
+        responses: {
+          response: function (ctx) {
+            return new Promise((resolve, reject) => {
+              setTimeout(() => {
+                ctx.body = 'test'
+                resolve()
+              }, 10)
+            })
+          }
+        }
+      }
+    ]
+  })
+  const server = http.createServer(app.callback())
+  server.listen(8100, () => {
+    request('http://localhost:8100/test')
+      .then(checkResponse(t, 200, /test/))
+      .then(server.close.bind(server))
+  })
+})