rspec rspec

let(:blog){Blog.new}         before(:each) do; blog=Blog.new; end
its(:title){should == nil}    @blog=Blog.new;@blog.title.should == nil
[1,2,3].should include(1)    [1,2,3].include?(1).should ==  true
{a: 1, b:2}.should have_key(:a)    {a: 1, b: 2}[:a].should_not == nil
[1,2,3].should have(3).items
blog.should be_real                blog.real?.should == true
expect{@blog.update_attribute(title: 'title')}.to change(@blog.title).from(nil).to("title")
expect{1/0}.to rails_error(ZeroDivisionError)
subject{Blog.new}; it/specify/example{should be_new_record}            
subject{Blog.new(title: 1)}; its(:title){should == 1}
@customer  = stub("customer"); @customer.stub(:name).and_return('zcy')
@customer.stub_chain(:foo, :bar, :baz).and_return("blah")