promisify and expose SuperTest agents

Agents persist cookies across requests. Promisify and expose this
interface at `exports.agent` to be compatible with SuperTest.

Fixes #1.

README.md

@@ -76,6 +76,22 @@ describe("GET /kittens", function () {
 });
 ```
 
+### Agents
+
+If you use a SuperTest agent to persist cookies, those are thenable too:
+
+```js
+var agent = require("supertest-as-promised").agent(app);
+
+agent
+  .get("/ugly-kitteh")
+  .expect(404)
+  .then(function () {
+    // ...
+  })
+```
+
+
 ### Promisey goodness
 
 To start, only the `then` method is exposed. But once you've called `.then`

index.js

@@ -1,4 +1,4 @@
-var _ = require("lodash")
+var methods = require("methods")
   , Promise = require("bluebird")
   , supertest = require("supertest");
 
@@ -7,17 +7,29 @@ function then(onFulfilled, onRejected) {
     .then(onFulfilled, onRejected);
 }
 
-module.exports = function () {
-  // Let SuperTest work its magic on whatever arguments we receive
-  var request = supertest.apply(null, arguments);
+// Creates a new object that inherits from `factory`, where each HTTP method
+// (`get`, `post`, etc.) is overriden to inject a `then` method into the
+// returned `Test` instance.
+function extend(factory) {
+  var out = Object.create(factory);
 
-  // Wrap all SuperTest functions (`get`, `post`, etc.) so we can inject a
-  // `then` method into the returned `Test` instance
-  return _.mapValues(request, function wrap(fn) {
-    return function () {
-      var test = fn.apply(null, arguments);
+  methods.forEach(function (method) {
+    out[method] = function () {
+      var test = factory[method].apply(factory, arguments);
       test.then = then;
       return test;
     };
   });
+
+  return out;
+}
+
+module.exports = function () {
+  var request = supertest.apply(null, arguments);
+  return extend(request);
+};
+
+module.exports.agent = function () {
+  var agent = supertest.agent.apply(null, arguments);
+  return extend(agent);
 };

package.json

@@ -41,6 +41,6 @@
   },
   "dependencies": {
     "bluebird": "^1.2.4",
-    "lodash": "^2.4.1"
+    "methods": "^1.0.0"
   }
 }

test/index.js

@@ -31,14 +31,46 @@ describe("supertestAsPromised", function () {
       return request.get("/home").expect(500).should.eventually.be.rejected;
     });
   });
+
+  describe("TestAgent instances", function () {
+    var agent = supertestAsPromised.agent(server);
+
+    describe("#then", function () {
+      it("should return a promise", function () {
+        agent.get("/home").then().should.be.an.instanceOf(Promise);
+      });
+    });
+
+    it("should fulfill if all assertions pass", function () {
+      return agent.get("/home").expect(200).should.eventually.be.fulfilled;
+    });
+
+    it("should fulfill with the response", function () {
+      return agent.get("/home").then(function (res) {
+        res.text.should.equal("helo");
+      });
+    });
+
+    it("should reject if an assertion fails", function () {
+      return agent.get("/home").expect(500).should.eventually.be.rejected;
+    });
+  });
 });
 
 describe("supertest", function () {
-  var request = supertest(server);
-
   describe("Test instances", function () {
+    var request = supertest(server);
+
     it("should not be a promise", function () {
       request.get("/home").should.not.have.property("then");
     });
   });
+
+  describe("TestAgent instances", function () {
+    var agent = supertest.agent(server);
+
+    it("should not be a promise", function () {
+      agent.get("/home").should.not.have.property("then");
+    });
+  });
 });