RSpec Matcher

Introduction#

rspec-expectations ships with a number of built-in matchers. Each matcher can be used with expect(..).to or expect(..).not_to to define positive and negative expectations respectively on an object.

Equality matchers

compare using eq (==)

RSpec.describe "a string" do
  it "is equal to another string of the same value" do
    expect("this string").to eq("this string")
  end

  it "is not equal to another string of a different value" do
    expect("this string").not_to eq("a different string")
  end
end

RSpec.describe "an integer" do
  it "is equal to a float of the same value" do
    expect(5).to eq(5.0)
  end
end

When I run rspec then the output should contain “3 examples, 0 failures”

compare using ==

RSpec.describe "a string" do
  it "is equal to another string of the same value" do
    expect("this string").to be == "this string"
  end

  it "is not equal to another string of a different value" do
    expect("this string").not_to be == "a different string"
  end
end

RSpec.describe "an integer" do
  it "is equal to a float of the same value" do
    expect(5).to be == 5.0
  end
end

When I run rspec then the output should contain “3 examples, 0 failures”

compare using eql (eql?)

 RSpec.describe "an integer" do
  it "is equal to another integer of the same value" do
    expect(5).to eql(5)
  end

  it "is not equal to another integer of a different value" do
    expect(5).not_to eql(6)
  end

  it "is not equal to a float of the same value" do
    expect(5).not_to eql(5.0)
  end
end

When I run rspec then the output should contain “3 examples, 0 failures”

compare using equal (equal?)

RSpec.describe "a string" do
  it "is equal to itself" do
    string = "this string"
    expect(string).to equal(string)
  end

  it "is not equal to another string of the same value" do
    expect("this string").not_to equal("this string")
  end

  it "is not equal to another string of a different value" do
    expect("this string").not_to equal("a different string")
  end
end

When I run rspec then the output should contain “3 examples, 0 failures”

compare using be (equal?)

RSpec.describe "a string" do
  it "is equal to itself" do
    string = "this string"
    expect(string).to be(string)
  end

  it "is not equal to another string of the same value" do
    expect("this string").not_to be("this string")
  end

  it "is not equal to another string of a different value" do
    expect("this string").not_to be("a different string")
  end
end

When I run rspec then the output should contain “3 examples, 0 failures”