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require 'set'
module RSpec
module Matchers
module DSL
# Provides the context in which the block passed to RSpec::Matchers.define
# will be evaluated.
class Matcher
include RSpec::Matchers::Extensions::InstanceEvalWithArgs
include RSpec::Matchers::Pretty
include RSpec::Matchers
attr_reader :expected, :actual, :rescued_exception
attr_accessor :matcher_execution_context
# @api private
def initialize(name, &declarations)
@name = name
@declarations = declarations
@actual = nil
@diffable = false
@expected_exception, @rescued_exception = nil, nil
@match_for_should_not_block = nil
@messages = {}
end
PERSISTENT_INSTANCE_VARIABLES = [
:@name, :@declarations, :@diffable, :@messages,
:@match_block, :@match_for_should_not_block,
:@expected_exception
].to_set
# @api private
def for_expected(*expected)
@expected = expected
dup.instance_eval do
instance_variables.map {|ivar| ivar.intern}.each do |ivar|
instance_variable_set(ivar, nil) unless (PERSISTENT_INSTANCE_VARIABLES + [:@expected]).include?(ivar)
end
making_declared_methods_public do
instance_eval_with_args(*@expected, &@declarations)
end
self
end
end
# @api private
# Used internally by +should+ and +should_not+.
def matches?(actual)
@actual = actual
if @expected_exception
begin
instance_eval_with_args(actual, &@match_block)
true
rescue @expected_exception => @rescued_exception
false
end
else
begin
instance_eval_with_args(actual, &@match_block)
rescue RSpec::Expectations::ExpectationNotMetError
false
end
end
end
# Stores the block that is used to determine whether this matcher passes
# or fails. The block should return a boolean value. When the matcher is
# passed to `should` and the block returns `true`, then the expectation
# passes. Similarly, when the matcher is passed to `should_not` and the
# block returns `false`, then the expectation passes.
#
# Use `match_for_should` when used in conjuntion with
# `match_for_should_not`.
#
# @example
#
# RSpec::Matchers.define :be_even do
# match do |actual|
# actual.even?
# end
# end
#
# 4.should be_even # passes
# 3.should_not be_even # passes
# 3.should be_even # fails
# 4.should_not be_even # fails
#
# @yield [Object] actual the actual value (or receiver of should)
def match(&block)
@match_block = block
end
alias_method :match_for_should, :match
# Use this to define the block for a negative expectation (`should_not`)
# when the positive and negative forms require different handling. This
# is rarely necessary, but can be helpful, for example, when specifying
# asynchronous processes that require different timeouts.
#
# @yield [Object] actual the actual value (or receiver of should)
def match_for_should_not(&block)
@match_for_should_not_block = block
end
# Use this instead of `match` when the block will raise an exception
# rather than returning false to indicate a failure.
#
# @example
#
# RSpec::Matchers.define :accept_as_valid do |candidate_address|
# match_unless_raises ValidationException do |validator|
# validator.validate(candidate_address)
# end
# end
#
# email_validator.should accept_as_valid("person@company.com")
def match_unless_raises(exception=Exception, &block)
@expected_exception = exception
match(&block)
end
# Customize the failure messsage to use when this matcher is invoked with
# `should`. Only use this when the message generated by default doesn't
# suit your needs.
#
# @example
#
# RSpec::Matchers.define :have_strength do |expected|
# match { ... }
#
# failure_message_for_should do |actual|
# "Expected strength of #{expected}, but had #{actual.strength}"
# end
# end
#
# @yield [Object] actual the actual object
def failure_message_for_should(&block)
cache_or_call_cached(:failure_message_for_should, &block)
end
# Customize the failure messsage to use when this matcher is invoked with
# `should_not`. Only use this when the message generated by default
# doesn't suit your needs.
#
# @example
#
# RSpec::Matchers.define :have_strength do |expected|
# match { ... }
#
# failure_message_for_should_not do |actual|
# "Expected not to have strength of #{expected}, but did"
# end
# end
#
# @yield [Object] actual the actual object
# @yield [Object] actual the actual object
def failure_message_for_should_not(&block)
cache_or_call_cached(:failure_message_for_should_not, &block)
end
# Customize the description to use for one-liners. Only use this when
# the description generated by default doesn't suit your needs.
#
# @example
#
# RSpec::Matchers.define :qualify_for do |expected|
# match { ... }
#
# description do
# "qualify for #{expected}"
# end
# end
def description(&block)
cache_or_call_cached(:description, &block)
end
# Tells the matcher to diff the actual and expected values in the failure
# message.
def diffable
@diffable = true
end
# Convenience for defining methods on this matcher to create a fluent
# interface. The trick about fluent interfaces is that each method must
# return self in order to chain methods together. `chain` handles that
# for you.
#
# @example
#
# RSpec::Matchers.define :have_errors_on do |key|
# chain :with do |message|
# @message = message
# end
#
# match do |actual|
# actual.errors[key] == @message
# end
# end
#
# minor.should have_errors_on(:age).with("Not old enough to participate")
def chain(method, &block)
define_method method do |*args|
block.call(*args)
self
end
end
# @api private
# Used internally by objects returns by +should+ and +should_not+.
def diffable?
@diffable
end
# @api private
# Used internally by +should_not+
def does_not_match?(actual)
@actual = actual
@match_for_should_not_block ?
instance_eval_with_args(actual, &@match_for_should_not_block) :
!matches?(actual)
end
def respond_to?(method, include_private=false)
super || @matcher_execution_context.respond_to?(method, include_private)
end
private
def method_missing(method, *args, &block)
if @matcher_execution_context.respond_to?(method)
@matcher_execution_context.send method, *args, &block
else
super(method, *args, &block)
end
end
def include(*args)
singleton_class.__send__(:include, *args)
end
def define_method(name, &block)
singleton_class.__send__(:define_method, name, &block)
end
def making_declared_methods_public
# Our home-grown instance_exec in ruby 1.8.6 results in any methods
# declared in the block eval'd by instance_exec in the block to which we
# are yielding here are scoped private. This is NOT the case for Ruby
# 1.8.7 or 1.9.
#
# Also, due some crazy scoping that I don't understand, these methods
# are actually available in the specs (something about the matcher being
# defined in the scope of RSpec::Matchers or within an example), so not
# doing the following will not cause specs to fail, but they *will*
# cause features to fail and that will make users unhappy. So don't.
orig_private_methods = private_methods
yield
(private_methods - orig_private_methods).each {|m| singleton_class.__send__ :public, m}
end
def cache_or_call_cached(key, &block)
block ? cache(key, &block) : call_cached(key)
end
def cache(key, &block)
@messages[key] = block
end
def call_cached(key)
if @messages.has_key?(key)
@messages[key].arity == 1 ? @messages[key].call(@actual) : @messages[key].call
else
send("default_#{key}")
end
end
def default_description
"#{name_to_sentence}#{expected_to_sentence}"
end
def default_failure_message_for_should
"expected #{actual.inspect} to #{name_to_sentence}#{expected_to_sentence}"
end
def default_failure_message_for_should_not
"expected #{actual.inspect} not to #{name_to_sentence}#{expected_to_sentence}"
end
unless method_defined?(:singleton_class)
def singleton_class
class << self; self; end
end
end
end
end
end
end
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