RSPEC TESTCASES FOR MODEL VALIDATIONS IN RAILS

describe User do
   before(:each) do
    @user_new = { :name => "chinna",:email => "chinna@yopmail.com",:password => "chinnaram",:password_confirmation => "chinnaram"}
   end
it "should create a new user details" do
     @user_attr = User.create!(@user_new)
end

##validations in your model ###########
User.rb(your model your mention like that....)
validates :name,:email,:presence => true
validates :name,:uniqueness => true
validates_attachment_content_type :image, :content_type => ['image/jpeg', 'image/png','image/pjpeg','image/x-png','image/gif']


###validation for name presence

it "should require a name" do
     user = User.new(@user_attr.merge(:name => ""))
     user.should_not be_valid
  end

#validation for email presence

 it "should require a email" do
     user = User.new(@user_attr.merge(:email => ""))
     user.should_not be_valid
  end

#validation for name uniqueness
 it "should require a unique name" do
     user = User.create!(@user_attr)
     user_new1 = User.new(@user_attr.merge(:name => "chinna"))
     user_new1.should_not be_valid
  end

# validation for image  attchement

   it { should have_attached_file(:image) }
  it {
       should validate_attachment_content_type(:image).
        allowing('image/jpeg','image/png','image/pjpeg','image/x-png','image/gif')
       }
end