# This file contains things needed to map Test::Unit status objects to 
# Exceptions, Exception related infrastructure and similar things.
# 
# See Contract::ContractException, Contract::ContractMismatch and
# Contract::ContractError.


class Contract < Test::Unit::TestCase
  # Exceptions raised by Contract contain some useful meta-information.
  # This module is mixed into Exceptions that provide such information.
  module ContractException
    def ce_initialize(original_message, backtrace, test_object,
      test_method, test_contract, *more) # :nodoc:
      @original_message = original_message
      message = original_message.dup
      detail = " for #{test_object.inspect} in " +
        "#{test_contract.inspect}"
      message[/(\s*)[.!?]?\s*\Z/, 1] = detail
      Exception.instance_method(:initialize).bind(self).call(message)

      set_backtrace(backtrace)
      @test_object = test_object
      @test_method = test_method
      @test_contract = test_contract
    end
    private :ce_initialize

    # What object was tested when this Exception was raised?
    attr_reader :test_object
    # What method implemented that test?
    attr_reader :test_method
    # What contract was that method part of?
    attr_reader :test_contract
    # The original, unfiltered exception message.
    attr_reader :original_message
  end

  # Represents a failed test in a contract. This means that an object
  # simply does not fulfill one of the parts of a contract. Subclass of
  # TypeError.
  class ContractMismatch < TypeError
    def initialize(*args) # :nodoc:
      ce_initialize(*args)
    end

    include ContractException
  end

  # Represents an unexpected failure while processing a contract test.
  # This is more critical than ContractMismatch and usually means that
  # something is wrong with the test itself.
  class ContractError < StandardError
    def initialize(*args) # :nodoc:
      @type = args.pop
      ce_initialize(*args)
    end

    # The type of the original Exception that triggered the unexpected
    # failure.
    attr_reader :type

    include ContractException
  end


  # Maps a Test::Unit::Failure instance to an actual Exception with the
  # specified meta data.
  def self.failure_to_exception(failure, object, contract) # :nodoc:
    ContractMismatch.new(failure.message, failure.location, object,
      extract_method_name(failure.test_name), contract)
  end

  # Maps a Test::Unit::Error instance to an actual Exception with the
  # specified meta data.
  def self.error_to_exception(error, object, contract) # :nodoc:
    original = error.exception
    ContractError.new(original.message, original.backtrace, object,
      extract_method_name(error.test_name), contract, original.class)
  end

  # Maps a Test::Unit fault (either a Failure or Error) to an actual
  # exception with the specified meta data.
  def self.fault_to_exception(fault, *args) # :nodoc:
    if fault.is_a?(Test::Unit::Failure) then
      failure_to_exception(fault, *args)
    else
      error_to_exception(fault, *args)
    end
  end

  # Extracts the method name from a Test::Unit test_name style String.
  def self.extract_method_name(test_name) # :nodoc:
    test_name[/\A(.+?)\(.+?\)\Z/, 1]
  end
end