require File.expand_path(File.dirname(__FILE__) + '/edgecase') class AboutBlocks < EdgeCase::Koan def method_with_block result = yield result end def test_methods_can_take_blocks yielded_result = method_with_block { 1 + 2 } assert_equal __, yielded_result end def test_blocks_can_be_defined_with_do_end_too yielded_result = method_with_block do 1 + 2 end assert_equal __, yielded_result end # ------------------------------------------------------------------ def method_with_block_arguments yield("Jim") end def test_blocks_can_take_arguments result = method_with_block_arguments do |argument| assert_equal __, argument end end # ------------------------------------------------------------------ def many_yields yield(:peanut) yield(:butter) yield(:and) yield(:jelly) end def test_methods_can_call_yield_many_times result = [] many_yields { |item| result << item } assert_equal __, result end # ------------------------------------------------------------------ def yield_tester if block_given? yield else :no_block end end def test_methods_can_see_if_they_have_been_called_with_a_block assert_equal __, yield_tester { :with_block } assert_equal __, yield_tester end # ------------------------------------------------------------------ def test_block_can_affect_variables_in_the_code_where_they_are_created value = :initial_value method_with_block { value = :modified_in_a_block } assert_equal __, value end def test_blocks_can_be_assigned_to_variables_and_called_explicitly add_one = lambda { |n| n + 1 } assert_equal __, add_one.call(10) # Alternative calling sequence assert_equal __, add_one[10] end def test_stand_alone_blocks_can_be_passed_to_methods_expecting_blocks make_upper = lambda { |n| n.upcase } result = method_with_block_arguments(&make_upper) assert_equal __, result end # ------------------------------------------------------------------ def method_with_explicit_block(&block) block.call(10) end def test_methods_can_take_an_explicit_block_argument assert_equal __, method_with_explicit_block { |n| n * 2 } add_one = lambda { |n| n + 1 } assert_equal __, method_with_explicit_block(&add_one) end end