module RSpec::Expectations

RSpec::Expectations adds two instance methods to every object:

should(matcher=nil)
should_not(matcher=nil)

Both methods take an optional matcher object (See [RSpec::Matchers](../RSpec/Matchers)). When `should` is invoked with a matcher, it turns around and calls `matcher.matches?(self)`. For example, in the expression:

order.total.should eq(Money.new(5.55, :USD))

the `should` method invokes the equivalent of `eq.matches?(order.total)`. If `matches?` returns true, the expectation is met and execution continues. If `false`, then the spec fails with the message returned by `eq.failure_message_for_should`.

Given the expression:

order.entries.should_not include(entry)

the `should_not` method invokes the equivalent of `include.matches?(order.entries)`, but it interprets `false` as success, and `true` as a failure, using the message generated by `eq.failure_message_for_should_not`.

rspec-expectations ships with a standard set of useful matchers, and writing your own matchers is quite simple.

See [RSpec::Matchers](../RSpec/Matchers) for more information about the built-in matchers that ship with rspec-expectations, and how to write your own custom matchers.

Public Class Methods

differ() click to toggle source

@private

# File lib/rspec/expectations/fail_with.rb, line 5
def differ
  @differ ||= Differ.new
end
fail_with(message, expected=nil, actual=nil) click to toggle source

Raises an RSpec::Expectations::ExpectationNotMetError with message. @param [String] message @param [Object] expected @param [Object] actual

Adds a diff to the failure message when `expected` and `actual` are both present.

# File lib/rspec/expectations/fail_with.rb, line 16
def fail_with(message, expected=nil, actual=nil)
  if !message
    raise ArgumentError, "Failure message is nil. Does your matcher define the " +
                         "appropriate failure_message_for_* method to return a string?"
  end

  if actual && expected
    if all_strings?(actual, expected)
      if any_multiline_strings?(actual, expected)
        message << "\nDiff:" << differ.diff_as_string(coerce_to_string(actual), coerce_to_string(expected))
      end
    elsif no_procs?(actual, expected) && no_numbers?(actual, expected)
      message << "\nDiff:" << differ.diff_as_object(actual, expected)
    end
  end

  raise(RSpec::Expectations::ExpectationNotMetError.new(message))
end

Private Class Methods

all_strings?(*args) click to toggle source
# File lib/rspec/expectations/fail_with.rb, line 41
def all_strings?(*args)
  args.flatten.all? {|a| String === a}
end
any_multiline_strings?(*args) click to toggle source
# File lib/rspec/expectations/fail_with.rb, line 45
def any_multiline_strings?(*args)
  all_strings?(*args) && args.flatten.any? { |a| multiline?(a) }
end
coerce_to_string(string_or_array) click to toggle source
# File lib/rspec/expectations/fail_with.rb, line 53
def coerce_to_string(string_or_array)
  return string_or_array unless Array === string_or_array
  string_or_array.join(',')
end
multiline?(string) click to toggle source
# File lib/rspec/expectations/fail_with.rb, line 59
def multiline?(string)
  string.include?("\n".encode(string.encoding))
end
no_numbers?(*args) click to toggle source
# File lib/rspec/expectations/fail_with.rb, line 49
def no_numbers?(*args)
  args.flatten.none? {|a| Numeric === a}
end
no_procs?(*args) click to toggle source
# File lib/rspec/expectations/fail_with.rb, line 37
def no_procs?(*args)
  args.flatten.none? {|a| Proc === a}
end

Public Instance Methods

differ=(ignore) click to toggle source

@deprecated (no replacement)

# File lib/rspec/expectations/extensions/object.rb, line 33
def differ=(ignore)
  RSpec.deprecate("RSpec::Expectations.differ=(differ)", "nothing at all (diffing is now automatic and no longer configurable)")
end