Module: RSpec::Matchers

### Home Classes Methods

### In Files

- lib/rspec/matchers.rb
- lib/rspec/matchers/be_close.rb
- lib/rspec/matchers/built_in.rb
- lib/rspec/matchers/built_in/base_matcher.rb
- lib/rspec/matchers/built_in/be.rb
- lib/rspec/matchers/built_in/be_instance_of.rb
- lib/rspec/matchers/built_in/be_kind_of.rb
- lib/rspec/matchers/built_in/be_within.rb
- lib/rspec/matchers/built_in/change.rb
- lib/rspec/matchers/built_in/cover.rb
- lib/rspec/matchers/built_in/eq.rb
- lib/rspec/matchers/built_in/eql.rb
- lib/rspec/matchers/built_in/equal.rb
- lib/rspec/matchers/built_in/exist.rb
- lib/rspec/matchers/built_in/has.rb
- lib/rspec/matchers/built_in/have.rb
- lib/rspec/matchers/built_in/include.rb
- lib/rspec/matchers/built_in/match.rb
- lib/rspec/matchers/built_in/match_array.rb
- lib/rspec/matchers/built_in/raise_error.rb
- lib/rspec/matchers/built_in/respond_to.rb
- lib/rspec/matchers/built_in/satisfy.rb
- lib/rspec/matchers/built_in/start_and_end_with.rb
- lib/rspec/matchers/built_in/throw_symbol.rb
- lib/rspec/matchers/built_in/yield.rb
- lib/rspec/matchers/configuration.rb
- lib/rspec/matchers/dsl.rb
- lib/rspec/matchers/extensions/instance_eval_with_args.rb
- lib/rspec/matchers/generated_descriptions.rb
- lib/rspec/matchers/matcher.rb
- lib/rspec/matchers/method_missing.rb
- lib/rspec/matchers/operator_matcher.rb
- lib/rspec/matchers/pretty.rb

### Namespace

- MODULE RSpec::Matchers::BuiltIn
- MODULE RSpec::Matchers::DSL
- MODULE RSpec::Matchers::Extensions
- MODULE RSpec::Matchers::Pretty
- CLASS RSpec::Matchers::Configuration
- CLASS RSpec::Matchers::OperatorMatcher

### Methods

- ::clear_generated_description
- ::configuration
- ::generated_description
- ::is_a_matcher?
- #be
- #be_a
- #be_a_kind_of
- #be_an
- #be_an_instance_of
- #be_close
- #be_false
- #be_instance_of
- #be_kind_of
- #be_nil
- #be_true
- #be_within
- #change
- #cover
- #end_with
- #eq
- #eql
- #equal
- #exist
- #have
- #have_at_least
- #have_at_most
- #have_exactly
- #include
- #match
- #match_array
- #match_regex
- #raise_error
- #raise_exception
- #respond_to
- #satisfy
- #start_with
- #throw_symbol
- #yield_control
- #yield_successive_args
- #yield_with_args
- #yield_with_no_args

### Class/Module Index

Quicksearch

- RSpec
- RSpec::Expectations
- RSpec::Expectations::DeprecatedConstants
- RSpec::Expectations::Deprecation
- RSpec::Expectations::Differ
- RSpec::Expectations::ExpectationHandler
- RSpec::Expectations::ExpectationNotMetError
- RSpec::Expectations::ExpectationTarget
- RSpec::Expectations::NegativeExpectationHandler
- RSpec::Expectations::PositiveExpectationHandler
- RSpec::Expectations::Syntax
- RSpec::Expectations::Syntax::ExpectExpressionGenerator
- RSpec::Expectations::Syntax::ShouldExpressionGenerator
- RSpec::Expectations::Version
- RSpec::Matchers
- RSpec::Matchers::BuiltIn
- RSpec::Matchers::BuiltIn::BaseMatcher
- RSpec::Matchers::BuiltIn::Be
- RSpec::Matchers::BuiltIn::BeAKindOf
- RSpec::Matchers::BuiltIn::BeAnInstanceOf
- RSpec::Matchers::BuiltIn::BeComparedTo
- RSpec::Matchers::BuiltIn::BeFalse
- RSpec::Matchers::BuiltIn::BeHelpers
- RSpec::Matchers::BuiltIn::BeNil
- RSpec::Matchers::BuiltIn::BePredicate
- RSpec::Matchers::BuiltIn::BeTrue
- RSpec::Matchers::BuiltIn::BeWithin
- RSpec::Matchers::BuiltIn::Change
- RSpec::Matchers::BuiltIn::Cover
- RSpec::Matchers::BuiltIn::EndWith
- RSpec::Matchers::BuiltIn::Eq
- RSpec::Matchers::BuiltIn::Eql
- RSpec::Matchers::BuiltIn::Equal
- RSpec::Matchers::BuiltIn::Exist
- RSpec::Matchers::BuiltIn::Has
- RSpec::Matchers::BuiltIn::Have
- RSpec::Matchers::BuiltIn::Include
- RSpec::Matchers::BuiltIn::Match
- RSpec::Matchers::BuiltIn::MatchArray
- RSpec::Matchers::BuiltIn::NegativeOperatorMatcher
- RSpec::Matchers::BuiltIn::PositiveOperatorMatcher
- RSpec::Matchers::BuiltIn::RaiseError
- RSpec::Matchers::BuiltIn::RespondTo
- RSpec::Matchers::BuiltIn::Satisfy
- RSpec::Matchers::BuiltIn::StartAndEndWith
- RSpec::Matchers::BuiltIn::StartWith
- RSpec::Matchers::BuiltIn::ThrowSymbol
- RSpec::Matchers::BuiltIn::YieldControl
- RSpec::Matchers::BuiltIn::YieldProbe
- RSpec::Matchers::BuiltIn::YieldSuccessiveArgs
- RSpec::Matchers::BuiltIn::YieldWithArgs
- RSpec::Matchers::BuiltIn::YieldWithNoArgs
- RSpec::Matchers::Configuration
- RSpec::Matchers::DSL
- RSpec::Matchers::DSL::Matcher
- RSpec::Matchers::Extensions
- RSpec::Matchers::Extensions::InstanceEvalWithArgs
- RSpec::Matchers::OperatorMatcher
- RSpec::Matchers::Pretty
- Array

No matching classes.

# RSpec::Matchers

RSpec::Matchers provides a number of useful matchers we use to define expectations. A matcher is any object that responds to the following:

    matches?(actual)
    failure_message_for_should

These methods are also part of the matcher protocol, but are optional:

    does_not_match?(actual)
    failure_message_for_should_not
    description

## Predicates

In addition to matchers that are defined explicitly, RSpec will create custom matchers on the fly for any arbitrary predicate, giving your specs a much more natural language feel.

A Ruby predicate is a method that ends with a "?" and returns true or false. Common examples are `empty?`, `nil?`, and `instance_of?`.

All you need to do is write `expect(..).to be_` followed by the predicate without the question mark, and RSpec will figure it out from there. For example:

    expect([]).to be_empty     # => [].empty?() | passes
    expect([]).not_to be_empty # => [].empty?() | fails

In addtion to prefixing the predicate matchers with "be_", you can also use "be_a_" and "be_an_", making your specs read much more naturally:

    expect("a string").to be_an_instance_of(String) # =>"a string".instance_of?(String) # passes

    expect(3).to be_a_kind_of(Fixnum)        # => 3.kind_of?(Numeric)     | passes
    expect(3).to be_a_kind_of(Numeric)       # => 3.kind_of?(Numeric)     | passes
    expect(3).to be_an_instance_of(Fixnum)   # => 3.instance_of?(Fixnum)  | passes
    expect(3).not_to be_an_instance_of(Numeric) # => 3.instance_of?(Numeric) | fails

RSpec will also create custom matchers for predicates like `has_key?`. To use this feature, just state that the object should have_key(:key) and RSpec will call has_key?(:key) on the target. For example:

    expect(:a => "A").to have_key(:a)
    expect(:a => "A").to have_key(:b) # fails

You can use this feature to invoke any predicate that begins with "has_", whether it is part of the Ruby libraries (like `Hash#has_key?`) or a method you wrote on your own class.

## Custom Matchers

When you find that none of the stock matchers provide a natural feeling expectation, you can very easily write your own using RSpec's matcher DSL or writing one from scratch.

### Matcher DSL

Imagine that you are writing a game in which players can be in various zones on a virtual board. To specify that bob should be in zone 4, you could say:

    expect(bob.current_zone).to eql(Zone.new("4"))

But you might find it more expressive to say:

    expect(bob).to be_in_zone("4")

and/or

    expect(bob).not_to be_in_zone("3")

You can create such a matcher like so:

    RSpec::Matchers.define :be_in_zone do |zone|
      match do |player|
        player.in_zone?(zone)
      end
    end

This will generate a `be_in_zone` method that returns a matcher with logical default messages for failures. You can override the failure messages and the generated description as follows:

    RSpec::Matchers.define :be_in_zone do |zone|
      match do |player|
        player.in_zone?(zone)
      end

      failure_message_for_should do |player|
        # generate and return the appropriate string.
      end

      failure_message_for_should_not do |player|
        # generate and return the appropriate string.
      end

      description do
        # generate and return the appropriate string.
      end
    end

Each of the message-generation methods has access to the block arguments passed to the `create` method (in this case, `zone`). The failure message methods (`failure_message_for_should` and `failure_message_for_should_not`) are passed the actual value (the receiver of `expect(..)` or `expect(..).not_to`).

### Custom Matcher from scratch

You could also write a custom matcher from scratch, as follows:

    class BeInZone
      def initialize(expected)
        @expected = expected
      end

      def matches?(target)
        @target = target
        @target.current_zone.eql?(Zone.new(@expected))
      end

      def failure_message_for_should
        "expected #{@target.inspect} to be in Zone #{@expected}"
      end

      def failure_message_for_should_not
        "expected #{@target.inspect} not to be in Zone #{@expected}"
      end
    end

... and a method like this:

    def be_in_zone(expected)
      BeInZone.new(expected)
    end

And then expose the method to your specs. This is normally done by including the method and the class in a module, which is then included in your spec:

    module CustomGameMatchers
      class BeInZone
        # ...
      end

      def be_in_zone(expected)
        # ...
      end
    end

    describe "Player behaviour" do
      include CustomGameMatchers
      # ...
    end

or you can include in globally in a spec_helper.rb file `require`d from your spec file(s):

    RSpec::configure do |config|
      config.include(CustomGameMatchers)
    end

### Attributes

last_matcher[RW]
last_should[RW]

### Public Class Methods

clear_generated_description() click to toggle source

    # File lib/rspec/matchers/generated_descriptions.rb, line 7
    def self.clear_generated_description
      self.last_matcher = nil
      self.last_should = nil
    end

configuration() click to toggle source

The configuration object @return [RSpec::Matchers::Configuration] the configuration object

    # File lib/rspec/matchers/configuration.rb, line 100
    def self.configuration
      @configuration ||= Configuration.new
    end

generated_description() click to toggle source

    # File lib/rspec/matchers/generated_descriptions.rb, line 12
    def self.generated_description
      return nil if last_should.nil?
      "#{last_should.to_s.gsub('_',' ')} #{last_description}"
    end

is_a_matcher?(obj) click to toggle source

@api private

    # File lib/rspec/matchers.rb, line 178
    def self.is_a_matcher?(obj)
      return true  if ::RSpec::Matchers::BuiltIn::BaseMatcher === obj
      return false if obj.respond_to?(:i_respond_to_everything_so_im_not_really_a_matcher)
      return false unless obj.respond_to?(:matches?)

      obj.respond_to?(:failure_message_for_should) || obj.respond_to?(:failure_message)
    end

### Public Instance Methods

be(*args) click to toggle source

@example

    expect(actual).to     be_true
    expect(actual).to     be_false
    expect(actual).to     be_nil
    expect(actual).to     be_[arbitrary_predicate](*args)
    expect(actual).not_to be_nil
    expect(actual).not_to be_[arbitrary_predicate](*args)

Given true, false, or nil, will pass if actual value is true, false or nil (respectively). Given no args means the caller should satisfy an if condition (to be or not to be).

Predicates are any Ruby method that ends in a "?" and returns true or false. Given be_ followed by arbitrary_predicate (without the "?"), RSpec will match convert that into a query against the target object.

The arbitrary_predicate feature will handle any predicate prefixed with "be_an_" (e.g. be_an_instance_of), "be_a_" (e.g. be_a_kind_of) or "be_" (e.g. be_empty), letting you choose the prefix that best suits the predicate.

    # File lib/rspec/matchers.rb, line 221
    def be(*args)
      args.empty? ?
        Matchers::BuiltIn::Be.new : equal(*args)
    end

be_a(klass) click to toggle source

passes if target.kind_of?(klass)

    # File lib/rspec/matchers.rb, line 227
    def be_a(klass)
      be_a_kind_of(klass)
    end

Also aliased as: be_an
be_a_kind_of(expected) click to toggle source

Passes if actual.kind_of?(expected)

@example

    expect(5).to     be_a_kind_of(Fixnum)
    expect(5).to     be_a_kind_of(Numeric)
    expect(5).not_to be_a_kind_of(Float)

    # File lib/rspec/matchers.rb, line 253
    def be_a_kind_of(expected)
      BuiltIn::BeAKindOf.new(expected)
    end

Also aliased as: be_kind_of
be_an(klass) click to toggle source
Alias for: be_a
be_an_instance_of(expected) click to toggle source

Passes if actual.instance_of?(expected)

@example

    expect(5).to     be_an_instance_of(Fixnum)
    expect(5).not_to be_an_instance_of(Numeric)
    expect(5).not_to be_an_instance_of(Float)

    # File lib/rspec/matchers.rb, line 240
    def be_an_instance_of(expected)
      BuiltIn::BeAnInstanceOf.new(expected)
    end

Also aliased as: be_instance_of
be_close(expected, delta) click to toggle source

@deprecated use `be_within` instead.

    # File lib/rspec/matchers/be_close.rb, line 4
    def be_close(expected, delta)
      RSpec.deprecate("be_close(#{expected}, #{delta})", :replacement => "be_within(#{delta}).of(#{expected})")
      be_within(delta).of(expected)
    end

be_false() click to toggle source

Passes if actual is falsy (false or nil)

    # File lib/rspec/matchers.rb, line 192
    def be_false
      BuiltIn::BeFalse.new
    end

be_instance_of(expected) click to toggle source
Alias for: be_an_instance_of
be_kind_of(expected) click to toggle source
Alias for: be_a_kind_of
be_nil() click to toggle source

Passes if actual is nil

    # File lib/rspec/matchers.rb, line 197
    def be_nil
      BuiltIn::BeNil.new
    end

be_true() click to toggle source

Passes if actual is truthy (anything but false or nil)

    # File lib/rspec/matchers.rb, line 187
    def be_true
      BuiltIn::BeTrue.new
    end

be_within(delta) click to toggle source

Passes if actual == expected +/- delta

@example

    expect(result).to     be_within(0.5).of(3.0)
    expect(result).not_to be_within(0.5).of(3.0)

    # File lib/rspec/matchers.rb, line 265
    def be_within(delta)
      BuiltIn::BeWithin.new(delta)
    end

change(receiver=nil, message=nil, &block) click to toggle source

Applied to a proc, specifies that its execution will cause some value to change.

@param [Object] receiver @param [Symbol] message the message to send the receiver

You can either pass `receiver` and `message`, or a block, but not both.

When passing a block, it must use the `{ ... }` format, not do/end, as `{ ... }` binds to the `change` method, whereas do/end would errantly bind to the +expect(..)+ or +expect(..).not_to+ method.

@example

    expect {
      team.add_player(player)
    }.to change(roster, :count)

    expect {
      team.add_player(player)
    }.to change(roster, :count).by(1)

    expect {
      team.add_player(player)
    }.to change(roster, :count).by_at_least(1)

    expect {
      team.add_player(player)
    }.to change(roster, :count).by_at_most(1)

    string = "string"
    expect {
      string.reverse!
    }.to change { string }.from("string").to("gnirts")

    string = "string"
    expect {
      string
    }.not_to change { string }

    expect {
      person.happy_birthday
    }.to change(person, :birthday).from(32).to(33)

    expect {
      employee.develop_great_new_social_networking_app
    }.to change(employee, :title).from("Mail Clerk").to("CEO")

    expect {
      doctor.leave_office
    }.to change(doctor, :sign).from(/is in/).to(/is out/)

    user = User.new(:type => "admin")
    expect {
      user.symbolize_type
    }.to change(user, :type).from(String).to(Symbol)

## Notes

Evaluates `receiver.message` or `block` before and after it evaluates the block passed to `expect`.

`expect( ... ).not_to change` only supports the form with no subsequent calls to `by`, `by_at_least`, `by_at_most`, `to` or `from`.

    # File lib/rspec/matchers.rb, line 335
    def change(receiver=nil, message=nil, &block)
      BuiltIn::Change.new(receiver, message, &block)
    end

cover(*values) click to toggle source

Passes if actual covers expected. This works for Ranges. You can also pass in multiple args and it will only pass if all args are found in Range.

@example

    expect(1..10).to     cover(5)
    expect(1..10).to     cover(4, 6)
    expect(1..10).to     cover(4, 6, 11) # fails
    expect(1..10).not_to cover(11)
    expect(1..10).not_to cover(5)        # fails

### Warning | Ruby >= 1.9 only

    # File lib/rspec/matchers.rb, line 351
    def cover(*values)
      BuiltIn::Cover.new(*values)
    end

end_with(*expected) click to toggle source

Matches if the actual value ends with the expected value(s). In the case of a string, matches against the last `expected.length` characters of the actual string. In the case of an array, matches against the last `expected.length` elements of the actual array.

@example

    expect("this string").to   end_with "string"
    expect([0, 1, 2, 3, 4]).to end_with 4
    expect([0, 2, 3, 4, 4]).to end_with 3, 4

    # File lib/rspec/matchers.rb, line 365
    def end_with(*expected)
      BuiltIn::EndWith.new(*expected)
    end

eq(expected) click to toggle source

Passes if `actual == expected`.

See www.ruby-doc.org/core/classes/Object.html#M001057 for more information about equality in Ruby.

@example

    expect(5).to     eq(5)
    expect(5).not_to eq(3)

    # File lib/rspec/matchers.rb, line 378
    def eq(expected)
      BuiltIn::Eq.new(expected)
    end

eql(expected) click to toggle source

Passes if +actual.eql?(expected)+

See www.ruby-doc.org/core/classes/Object.html#M001057 for more information about equality in Ruby.

@example

    expect(5).to     eql(5)
    expect(5).not_to eql(3)

    # File lib/rspec/matchers.rb, line 391
    def eql(expected)
      BuiltIn::Eql.new(expected)
    end

equal(expected) click to toggle source

Passes if `actual.equal?(expected)` (object identity).

See www.ruby-doc.org/core/classes/Object.html#M001057 for more information about equality in Ruby.

@example

    expect(5).to       equal(5)   # Fixnums are equal
    expect("5").not_to equal("5") # Strings that look the same are not the same object

    # File lib/rspec/matchers.rb, line 404
    def equal(expected)
      BuiltIn::Equal.new(expected)
    end

exist(*args) click to toggle source

Passes if `actual.exist?` or `actual.exists?`

@example

    expect(File).to exist("path/to/file")

    # File lib/rspec/matchers.rb, line 412
    def exist(*args)
      BuiltIn::Exist.new(*args)
    end

have(n) click to toggle source

Passes if receiver is a collection with the submitted number of items OR if the receiver OWNS a collection with the submitted number of items.

If the receiver OWNS the collection, you must use the name of the collection. So if a `Team` instance has a collection named `players`, you must use that name to set the expectation.

If the receiver IS the collection, you can use any name you like for `named_collection`. We'd recommend using either "elements", "members", or "items" as these are all standard ways of describing the things IN a collection.

This also works for Strings, letting you set expectations about their lengths.

@example

    # Passes if team.players.size == 11
    expect(team).to have(11).players

    # Passes if [1,2,3].length == 3
    expect([1,2,3]).to have(3).items #"items" is pure sugar

    # Passes if ['a', 'b', 'c'].count == 3
    expect([1,2,3]).to have(3).items #"items" is pure sugar

    # Passes if "this string".length == 11
    expect("this string").to have(11).characters #"characters" is pure sugar

    # File lib/rspec/matchers.rb, line 444
    def have(n)
      BuiltIn::Have.new(n)
    end

Also aliased as: have_exactly
have_at_least(n) click to toggle source

Exactly like have() with >=.

@example

    expect("this").to have_at_least(3).letters

### Warning:

`expect(..).not_to have_at_least` is not supported

    # File lib/rspec/matchers.rb, line 457
    def have_at_least(n)
      BuiltIn::Have.new(n, :at_least)
    end

have_at_most(n) click to toggle source

Exactly like have() with <=.

@example

    expect("this").to have_at_most(4).letters

### Warning:

`expect(..).not_to have_at_most` is not supported

    # File lib/rspec/matchers.rb, line 469
    def have_at_most(n)
      BuiltIn::Have.new(n, :at_most)
    end

have_exactly(n) click to toggle source
Alias for: have
include(*expected) click to toggle source

Passes if actual includes expected. This works for collections and Strings. You can also pass in multiple args and it will only pass if all args are found in collection.

@example

    expect([1,2,3]).to      include(3)
    expect([1,2,3]).to      include(2,3)
    expect([1,2,3]).to      include(2,3,4) # fails
    expect([1,2,3]).not_to  include(4)
    expect("spread").to     include("read")
    expect("spread").not_to include("red")

    # File lib/rspec/matchers.rb, line 485
    def include(*expected)
      BuiltIn::Include.new(*expected)
    end

match(expected) click to toggle source

Given a Regexp or String, passes if actual.match(pattern)

@example

    expect(email).to   match(/^([^\s]+)((?:[-a-z0-9]+\.)+[a-z]{2,})$/i)
    expect(email).to   match("@example.com")
    expect(zipcode).to match_regex(/\A\d{5}(-\d{4})?\z/)
    expect(zipcode).to match_regex("90210")

@note Due to Ruby's method dispatch mechanism, using the `match` matcher within a custom matcher defined via the matcher DSL (`RSpec::Matcher.define`) will result Ruby calling the wrong `match` method and raising an `ArgumentError`. Instead, use the aliased `match_regex` method.

    # File lib/rspec/matchers.rb, line 503
    def match(expected)
      BuiltIn::Match.new(expected)
    end

Also aliased as: match_regex
match_array(array) click to toggle source

Passes if actual contains all of the expected regardless of order. This works for collections. Pass in multiple args and it will only pass if all args are found in collection.

@note This is also available using the `=~` operator with `should`,

    but `=~` is not supported with `expect`.

@note This matcher only supports positive expectations.

    expect(..).not_to match_array(other_array) is not supported.

@example

    expect([1,2,3]).to match_array([1,2,3])
    expect([1,2,3]).to match_array([1,3,2])

    # File lib/rspec/matchers.rb, line 691
    def match_array(array)
      BuiltIn::MatchArray.new(array)
    end

match_regex(expected) click to toggle source
Alias for: match
raise_error(error=Exception, message=nil, &block) click to toggle source

With no args, matches if any error is raised. With a named error, matches only if that specific error is raised. With a named error and messsage specified as a String, matches only if both match. With a named error and messsage specified as a Regexp, matches only if both match. Pass an optional block to perform extra verifications on the exception matched

@example

    expect { do_something_risky }.to raise_error
    expect { do_something_risky }.to raise_error(PoorRiskDecisionError)
    expect { do_something_risky }.to raise_error(PoorRiskDecisionError) { |error| expect(error.data).to eq 42 }
    expect { do_something_risky }.to raise_error(PoorRiskDecisionError, "that was too risky")
    expect { do_something_risky }.to raise_error(PoorRiskDecisionError, /oo ri/)

    expect { do_something_risky }.not_to raise_error
    expect { do_something_risky }.not_to raise_error(PoorRiskDecisionError)
    expect { do_something_risky }.not_to raise_error(PoorRiskDecisionError, "that was too risky")
    expect { do_something_risky }.not_to raise_error(PoorRiskDecisionError, /oo ri/)

    # File lib/rspec/matchers.rb, line 527
    def raise_error(error=Exception, message=nil, &block)
      BuiltIn::RaiseError.new(error, message, &block)
    end

Also aliased as: raise_exception
raise_exception(error=Exception, message=nil, &block) click to toggle source
Alias for: raise_error
respond_to(*names) click to toggle source

Matches if the target object responds to all of the names provided. Names can be Strings or Symbols.

@example

expect("string").to respond_to(:length)

    # File lib/rspec/matchers.rb, line 540
    def respond_to(*names)
      BuiltIn::RespondTo.new(*names)
    end

satisfy(&block) click to toggle source

Passes if the submitted block returns true. Yields target to the block.

Generally speaking, this should be thought of as a last resort when you can't find any other way to specify the behaviour you wish to specify.

If you do find yourself in such a situation, you could always write a custom matcher, which would likely make your specs more expressive.

@example

    expect(5).to satisfy { |n| n > 3 }

    # File lib/rspec/matchers.rb, line 557
    def satisfy(&block)
      BuiltIn::Satisfy.new(&block)
    end

start_with(*expected) click to toggle source

Matches if the actual value starts with the expected value(s). In the case of a string, matches against the first `expected.length` characters of the actual string. In the case of an array, matches against the first `expected.length` elements of the actual array.

@example

    expect("this string").to   start_with "this s"
    expect([0, 1, 2, 3, 4]).to start_with 0
    expect([0, 2, 3, 4, 4]).to start_with 0, 1

    # File lib/rspec/matchers.rb, line 571
    def start_with(*expected)
      BuiltIn::StartWith.new(*expected)
    end

throw_symbol(expected_symbol=nil, expected_arg=nil) click to toggle source

Given no argument, matches if a proc throws any Symbol.

Given a Symbol, matches if the given proc throws the specified Symbol.

Given a Symbol and an arg, matches if the given proc throws the specified Symbol with the specified arg.

@example

    expect { do_something_risky }.to throw_symbol
    expect { do_something_risky }.to throw_symbol(:that_was_risky)
    expect { do_something_risky }.to throw_symbol(:that_was_risky, 'culprit')

    expect { do_something_risky }.not_to throw_symbol
    expect { do_something_risky }.not_to throw_symbol(:that_was_risky)
    expect { do_something_risky }.not_to throw_symbol(:that_was_risky, 'culprit')

    # File lib/rspec/matchers.rb, line 591
    def throw_symbol(expected_symbol=nil, expected_arg=nil)
      BuiltIn::ThrowSymbol.new(expected_symbol, expected_arg)
    end

yield_control() click to toggle source

Passes if the method called in the expect block yields, regardless of whether or not arguments are yielded.

@example

    expect { |b| 5.tap(&b) }.to yield_control
    expect { |b| "a".to_sym(&b) }.not_to yield_control

@note Your expect block must accept a parameter and pass it on to

    the method-under-test as a block.

@note This matcher is not designed for use with methods that yield

    multiple times.

    # File lib/rspec/matchers.rb, line 607
    def yield_control
      BuiltIn::YieldControl.new
    end

yield_successive_args(*args) click to toggle source

Designed for use with methods that repeatedly yield (such as iterators). Passes if the method called in the expect block yields multiple times with arguments matching those given.

Argument matching is done using `===` (the case match operator) and `==`. If the expected and actual arguments match with either operator, the matcher will pass.

@example

    expect { |b| [1, 2, 3].each(&b) }.to yield_successive_args(1, 2, 3)
    expect { |b| { :a => 1, :b => 2 }.each(&b) }.to yield_successive_args([:a, 1], [:b, 2])
    expect { |b| [1, 2, 3].each(&b) }.not_to yield_successive_args(1, 2)

@note Your expect block must accept a parameter and pass it on to

    the method-under-test as a block.

    # File lib/rspec/matchers.rb, line 673
    def yield_successive_args(*args)
      BuiltIn::YieldSuccessiveArgs.new(*args)
    end

yield_with_args(*args) click to toggle source

Given no arguments, matches if the method called in the expect block yields with arguments (regardless of what they are or how many there are).

Given arguments, matches if the method called in the expect block yields with arguments that match the given arguments.

Argument matching is done using `===` (the case match operator) and `==`. If the expected and actual arguments match with either operator, the matcher will pass.

@example

    expect { |b| 5.tap(&b) }.to yield_with_args # because #tap yields an arg
    expect { |b| 5.tap(&b) }.to yield_with_args(5) # because 5 == 5
    expect { |b| 5.tap(&b) }.to yield_with_args(Fixnum) # because Fixnum === 5
    expect { |b| File.open("f.txt", &b) }.to yield_with_args(/txt/) # because /txt/ === "f.txt"

    expect { |b| User.transaction(&b) }.not_to yield_with_args # because it yields no args
    expect { |b| 5.tap(&b) }.not_to yield_with_args(1, 2, 3)

@note Your expect block must accept a parameter and pass it on to

    the method-under-test as a block.

@note This matcher is not designed for use with methods that yield

    multiple times.

    # File lib/rspec/matchers.rb, line 653
    def yield_with_args(*args)
      BuiltIn::YieldWithArgs.new(*args)
    end

yield_with_no_args() click to toggle source

Passes if the method called in the expect block yields with no arguments. Fails if it does not yield, or yields with arguments.

@example

    expect { |b| User.transaction(&b) }.to yield_with_no_args
    expect { |b| 5.tap(&b) }.not_to yield_with_no_args # because it yields with `5`
    expect { |b| "a".to_sym(&b) }.not_to yield_with_no_args # because it does not yield

@note Your expect block must accept a parameter and pass it on to

    the method-under-test as a block.

@note This matcher is not designed for use with methods that yield

    multiple times.

    # File lib/rspec/matchers.rb, line 624
    def yield_with_no_args
      BuiltIn::YieldWithNoArgs.new
    end

[Validate]

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