Module: RSpec::Core::Let::ClassMethods

Public Instance methods

Generates a method whose return value is memoized after the first call.

Examples

 describe Thing do
   let(:thing) { Thing.new }

   it "does something" do
     # first invocation, executes block, memoizes and returns result
     thing.do_something

     # second invocation, returns the memoized value
     thing.should be_something
   end
 end

let!(name, &block)

Just like let(), except the block is invoked by an implicit before hook. This serves a dual purpose of setting up state and providing a memoized reference to that state.

Examples

 class Thing
   def self.count
     @count ||= 0
   end

   def self.count=(val)
     @count += val
   end

   def self.reset_count
     @count = 0
   end

   def initialize
     self.class.count += 1
   end
 end

 describe Thing do
   after(:each) { Thing.reset_count }

   context "using let" do
     let(:thing) { Thing.new }

     it "is not invoked implicitly" do
       Thing.count.should == 0
     end

     it "can be invoked explicitly" do
       thing
       Thing.count.should == 1
     end
   end

   context "using let!" do
     let!(:thing) { Thing.new }

     it "is invoked implicitly" do
       Thing.count.should == 1
     end

     it "returns memoized version on first invocation" do
       thing
       Thing.count.should == 1
     end
   end
 end