Minitest integration

rspec-expectations is a stand-alone gem that can be used without the rest of RSpec. If you like minitest as your test runner, but prefer RSpec's approach to expressing expectations, you can have both.

To integrate rspec-expectations with minitest, require rspec/expectations/minitest_integration.

Use rspec/expectations with minitest

Given a file named "rspec_expectations_test.rb" with:

require 'minitest/autorun'
require 'rspec/expectations/minitest_integration'

class RSpecExpectationsTest < Minitest::Test
  RSpec::Matchers.define :be_an_integer do
    match { |actual| Integer === actual }
  end

  def be_an_int
    # This is actually an internal rspec-expectations API, but is used
    # here to demonstrate that deprecation warnings from within
    # rspec-expectations work correctly without depending on rspec-core
    RSpec.deprecate(:be_an_int, :replacement => :be_an_integer)
    be_an_integer
  end

  def test_passing_expectation
    expect(1 + 3).to eq 4
  end

  def test_failing_expectation
    expect([1, 2]).to be_empty
  end

  def test_custom_matcher_with_deprecation_warning
    expect(1).to be_an_int
  end

  def test_using_aggregate_failures
    aggregate_failures do
      expect(1).to be_even
      expect(2).to be_odd
    end
  end
end

When I run ruby rspec_expectations_test.rb

Then the output should contain "4 runs, 5 assertions, 2 failures, 0 errors"

And the output should contain "expected [1, 2].empty? to be truthy, got false"

And the output should contain "be_an_int is deprecated"

And the output should contain "Got 2 failures from failure aggregation block".

Use rspec/expectations with minitest/spec

Given a file named "rspec_expectations_spec.rb" with:

require 'minitest/autorun'
require 'minitest/spec'
require 'rspec/expectations/minitest_integration'

describe "Using RSpec::Expectations with Minitest::Spec" do
  RSpec::Matchers.define :be_an_integer do
    match { |actual| Integer === actual }
  end

  it 'passes an expectation' do
    expect(1 + 3).to eq 4
  end

  it 'fails an expectation' do
    expect([1, 2]).to be_empty
  end

  it 'passes a block expectation' do
    expect { 1 / 0 }.to raise_error(ZeroDivisionError)
  end

  it 'fails a block expectation' do
    expect { 1 / 1 }.to raise_error(ZeroDivisionError)
  end

  it 'passes a negative expectation (using `not_to`)' do
    expect(1).not_to eq 2
  end

  it 'fails a negative expectation (using `to_not`)' do
    expect(1).to_not eq 1
  end

  it 'fails multiple expectations' do
    aggregate_failures do
      expect(1).to be_even
      expect(2).to be_odd
    end
  end

  it 'passes a minitest expectation' do
    expect(1 + 3).must_equal 4
  end

  it 'fails a minitest expectation' do
    expect([1, 2]).must_be :empty?
  end
end

When I run ruby rspec_expectations_spec.rb

Then the output should contain "9 runs, 10 assertions, 5 failures, 0 errors"

And the output should contain "expected [1, 2].empty? to be truthy, got false"

And the output should contain "expected ZeroDivisionError but nothing was raised"

And the output should contain "Got 2 failures from failure aggregation block"

And the output should contain "Expected [1, 2] to be empty?".