Implement sessions/create in JSON API

spec/controllers/api/v0/sessions_controller_spec.rb

@@ -0,0 +1,49 @@
+require 'spec_helper'
+
+describe Api::V0::SessionsController do
+  describe 'POST create' do
+    let(:user) { Factory.create(:user) }
+
+    def do_create
+      post :create, :format => :json, :session => {
+        :email    => user.email,
+        :password => user.password
+      }
+    end
+
+    context 'with valid credentials' do
+      before do
+        do_create
+      end
+
+      it 'signs the user in' do
+        controller.current_user.should == user
+      end
+
+      it 'assigns the user' do
+        assigns[:user].should == user
+      end
+    end
+
+    [:email, :password].each do |attr|
+      context "with invalid credentials (#{attr})" do
+        before do
+          user.stub(attr => user.send(attr) + '_INVALID')
+          do_create
+        end
+
+        it 'returns a not found response' do
+          response.should be_not_found
+        end
+
+        it 'returns an empty body' do
+          response.body.should be_empty
+        end
+
+        it 'assigns no user' do
+          assigns[:user].should be_nil
+        end
+      end
+    end
+  end
+end