Skip to content
Provides a readable API to express expected outcomes of a code example
Ruby Cucumber Shell
Find file
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Failed to load latest commit information.

RSpec Expectations Build Status Code Climate

RSpec::Expectations lets you express expected outcomes on an object in an example.

expect(account.balance).to eq(, :USD))


If you want to use rspec-expectations with rspec, just install the rspec gem and RubyGems will also install rspec-expectations for you (along with rspec-core and rspec-mocks):

gem install rspec

If you want to use rspec-expectations with another tool, like Test::Unit, Minitest, or Cucumber, you can install it directly:

gem install rspec-expectations

Basic usage

Here's an example using rspec-core:

describe Order do
  it "sums the prices of the items in its line items" do
    order =
    order.add_entry( =>
      :price =>, :USD)
    order.add_entry( =>
      :price =>, :USD),
      :quantity => 2
    expect( eq(, :USD))

The describe and it methods come from rspec-core. The Order, LineItem, Item and Money classes would be from your code. The last line of the example expresses an expected outcome. If ==, :USD), then the example passes. If not, it fails with a message like:

expected: #<Money @value=5.55 @currency=:USD>
     got: #<Money @value=1.11 @currency=:USD>

Built-in matchers


expect(actual).to eq(expected)  # passes if actual == expected
expect(actual).to eql(expected) # passes if actual.eql?(expected)

Note: The new expect syntax no longer supports == matcher.


expect(actual).to be(expected)    # passes if actual.equal?(expected)
expect(actual).to equal(expected) # passes if actual.equal?(expected)


expect(actual).to be >  expected
expect(actual).to be >= expected
expect(actual).to be <= expected
expect(actual).to be <  expected
expect(actual).to be_within(delta).of(expected)

Regular expressions

expect(actual).to match(/expression/)

Note: The new expect syntax no longer supports =~ matcher.


expect(actual).to be_an_instance_of(expected)
expect(actual).to be_a_kind_of(expected)


expect(actual).to be_true  # passes if actual is truthy (not nil or false)
expect(actual).to be_false # passes if actual is falsy (nil or false)
expect(actual).to be_nil   # passes if actual is nil

Expecting errors

expect { ... }.to raise_error
expect { ... }.to raise_error(ErrorClass)
expect { ... }.to raise_error("message")
expect { ... }.to raise_error(ErrorClass, "message")

Expecting throws

expect { ... }.to throw_symbol
expect { ... }.to throw_symbol(:symbol)
expect { ... }.to throw_symbol(:symbol, 'value')


expect { |b| 5.tap(&b) }.to yield_control # passes regardless of yielded args

expect { |b| yield_if_true(true, &b) }.to yield_with_no_args # passes only if no args are yielded

expect { |b| 5.tap(&b) }.to yield_with_args(5)
expect { |b| 5.tap(&b) }.to yield_with_args(Fixnum)
expect { |b| "a string".tap(&b) }.to yield_with_args(/str/)

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])

Predicate matchers

expect(actual).to be_xxx         # passes if
expect(actual).to have_xxx(:arg) # passes if actual.has_xxx?(:arg)

Ranges (Ruby >= 1.9 only)

expect(1..10).to cover(3)

Collection membership

expect(actual).to include(expected)
expect(actual).to start_with(expected)
expect(actual).to end_with(expected)


expect([1,2,3]).to include(1)
expect([1,2,3]).to include(1, 2)
expect([1,2,3]).to start_with(1)
expect([1,2,3]).to start_with(1,2)
expect([1,2,3]).to end_with(3)
expect([1,2,3]).to end_with(2,3)
expect({:a => 'b'}).to include(:a => 'b')
expect("this string").to include("is str")
expect("this string").to start_with("this")
expect("this string").to end_with("ring")

should syntax

In addition to the expect syntax, rspec-expectations continues to support the should syntax:

actual.should eq expected
actual).should be > 3
[1, 2, 3].should_not include 4

Motivation for expect

We added the expect syntax to resolve some edge case issues, most notably that objects whose definitions wipe out all but a few methods were throwing should and should_not away. expect solves that by not monkey patching those methods onto Kernel (or any global object).

See for a detailed explanation.

Using either expect or should or both

If you want your project to only use one of these syntaxes, you can configure it:

RSpec.configure do |config|
  config.expect_with :rspec do |c|
    c.syntax = :expect             # disables `should`
    # or
    c.syntax = :should             # disables `expect`
    # or
    c.syntax = [:should, :expect]  # enables both `should` and `expect`

See RSpec::Expectations::Syntax#expect for more information.


The one-liner syntax supported by rspec-core uses should even when config.syntax = :expect. It reads better than the alternative, and does not require a global monkey patch:

describe User do
  it { should validate_presence_of :email }

Also see

Something went wrong with that request. Please try again.