Module: Spec::Expectations

Defined in:
lib/spec/expectations.rb,
lib/spec/expectations/errors.rb,
lib/spec/expectations/handler.rb,
lib/spec/expectations/fail_with.rb,
lib/spec/runner/differs/default.rb

Overview

Spec::Expectations lets you set expectations on your objects.

result.should == 37
team.should have(11).players_on_the_field

How Expectations work.

Spec::Expectations adds two methods to Object:

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

Both methods take an optional Expression Matcher (See Spec::Matchers).

When should receives an Expression Matcher, it calls matches?(self). If it returns true, the spec passes and execution continues. If it returns false, then the spec fails with the message returned by matcher.failure_message.

Similarly, when should_not receives a matcher, it calls matches?(self). If it returns false, the spec passes and execution continues. If it returns true, then the spec fails with the message returned by matcher.negative_failure_message.

RSpec ships with a standard set of useful matchers, and writing your own matchers is quite simple. See Spec::Matchers for details.

Defined Under Namespace

Modules: Differs Classes: ExpectationNotMetError, InvalidMatcherError, NegativeExpectationHandler, PositiveExpectationHandler

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.differObject

Returns the value of attribute differ



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# File 'lib/spec/expectations/fail_with.rb', line 4

def differ
  @differ
end

Class Method Details

.fail_with(message, expected = nil, target = nil) ⇒ Object

raises a Spec::Expectations::ExpectationNotMetError with message

When a differ has been assigned and fail_with is passed expected and target, passes them to the differ to append a diff message to the failure message.



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# File 'lib/spec/expectations/fail_with.rb', line 11

def fail_with(message, expected=nil, target=nil) # :nodoc:
  if message.nil?
    raise ArgumentError, "Failure message is nil. Does your matcher define the " +
                         "appropriate failure_message_for_* method to return a string?"
  end
  if (Array === message) & (message.length == 3)
    ::Spec.warn(<<-NOTICE

*****************************************************************
DEPRECATION WARNING: you are using deprecated behaviour that will
be removed from a future version of RSpec.

* Support for matchers that return arrays from failure message
methods is deprecated.
* Instead, the matcher should return a string, and expose methods
for the expected() and actual() values.
*****************************************************************
NOTICE
    )
    message, expected, target = message[0], message[1], message[2]
  end
  unless (differ.nil? || expected.nil? || target.nil?)
    if expected.is_a?(String)
      message << "\n\n Diff:" << self.differ.diff_as_string(target.to_s, expected)
    elsif expected.is_a?(Hash) && target.is_a?(Hash)
      message << "\n\n Diff:" << self.differ.diff_as_hash(target, expected)
    elsif !target.is_a?(Proc)
      message << "\n\n Diff:" << self.differ.diff_as_object(target, expected)
    end
  end
  Kernel::raise(Spec::Expectations::ExpectationNotMetError.new(message))
end