Contents

require 'contract'

class StackContract < Contract

  post :push do |stack_pre, stack, exception, result, element|
    assert_nil(result)
    assert_equal(element, stack.top)
    assert_equal(stack.size, stack_pre.size + 1)
  end

  pre :pop do |stack|
    assert_operator(stack.size, :>=, 0)
  end

  post :pop do |stack_pre, stack, exception, result|
    if stack_pre.empty?
      assert_kind_of(Stack::NoPopForEmptyStack, exception)
    else
      assert_equal(stack_pre.top, result)
      assert_equal(stack_pre.size - 1, stack.size)
    end
  end

  pre :top do |stack|
    assert_operator(stack.size, :>=, 1)
  end

  post :top do |stack_pre, stack, exception, result|
    assert_equal(stack_pre.size, stack.size)
  end

  invariant do |stack|
    assert_operator(stack.size, :>=, 0)
  end

end

Version data entries

2 entries across 2 versions & 1 rubygems

Version	Path
armin-joellenbeck-rdbc-0.0.6	examples/stack_contract.rb
armin-joellenbeck-rdbc-0.0.7	examples/stack_contract.rb