Module: RSpec::Expectations

Defined in:
lib/rspec/expectations.rb,
lib/rspec/expectations/differ.rb,
lib/rspec/expectations/errors.rb,
lib/rspec/expectations/handler.rb,
lib/rspec/expectations/version.rb,
lib/rspec/expectations/fail_with.rb,
lib/rspec/expectations/extensions/object.rb

Overview

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

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

How Expectations work.

RSpec::Expectations adds two methods to Object:

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

Both methods take an optional Expression Matcher (See RSpec::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 RSpec::Matchers for details.

Defined Under Namespace

Modules: DeprecatedConstants, Version Classes: Differ, ExpectationNotMetError, InvalidMatcherError, NegativeExpectationHandler, PositiveExpectationHandler

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.differ ⇒ Object 



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# File 'lib/rspec/expectations/fail_with.rb', line 5

def differ
  @differ ||= Differ.new
end

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

Raises an RSpec::Expectations::ExpectationNotMetError with message. Adds a diff to the failure message when expected and actual are both present.

Parameters:

  • message (String)
  • expected (Object) (defaults to: nil)
  • actual (Object) (defaults to: nil)

Raises:



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# 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:" << self.differ.diff_as_string(actual, expected)
      end
    elsif no_procs?(actual, expected) && no_numbers?(actual, expected)
      message << "\nDiff:" << self.differ.diff_as_object(actual, expected)
    end
  end

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

Instance Method Details

#differ=(ignore) ⇒ Object

Deprecated.

(no replacement)



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# 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