Integrating with any test framework

rspec-mocks is a stand-alone gem that can be integrated with any test framework. The example below demonstrates using rspec-mocks with minitest, but these steps would apply when integrating rspec-mocks with any library or framework:

• Include RSpec::Mocks::ExampleMethods in your test context. This provides rspec-mocks' API.
• Call RSpec::Mocks.setup before a test begins.
• Call RSpec::Mocks.verify after a test completes to verify message expectations. Note that this step is optional; rspec-core, for example, skips this when an example has already failed.
• Call RSpec::Mocks.teardown after a test completes (and after verify) to cleanup. This must be called, even if an error has occurred, so it generally goes in an ensure clause.

Note: if you are using minitest, you'll probably want to use the built-in minitest integration.

Use rspec-mocks with Minitest

Given a file named "test/test_helper.rb" with:

require 'minitest/autorun'
require 'rspec/mocks'

module MinitestRSpecMocksIntegration
  include ::RSpec::Mocks::ExampleMethods

  def before_setup
    ::RSpec::Mocks.setup
    super
  end

  def after_teardown
    super
    ::RSpec::Mocks.verify
  ensure
    ::RSpec::Mocks.teardown
  end
end

Minitest::Test.send(:include, MinitestRSpecMocksIntegration)

And a file named "test/rspec_mocks_test.rb" with:

require 'test_helper'

class RSpecMocksTest < Minitest::Test
  def test_passing_positive_expectation
    dbl = double
    expect(dbl).to receive(:message)
    dbl.message
  end

  def test_failing_positive_expectation
    dbl = double
    expect(dbl).to receive(:message)
  end

  def test_passing_negative_expectation
    dbl = double
    expect(dbl).to_not receive(:message)
  end

  def test_failing_negative_expectation
    dbl = double
    expect(dbl).to_not receive(:message)
    dbl.message
  end

  def test_passing_positive_spy_expectation
    bond = spy
    bond.james
    expect(bond).to have_received(:james)
  end

  def test_failing_positive_spy_expectation
    bond = spy
    expect(bond).to have_received(:james)
  end

  def test_passing_negative_spy_expectation
    bond = spy
    expect(bond).not_to have_received(:james)
  end

  def test_failing_negative_spy_expectation
    bond = spy
    bond.james
    expect(bond).not_to have_received(:james)
  end
end

When I run ruby -Itest test/rspec_mocks_test.rb

Then it should fail with the following output:

| 1) Error: | | RSpecMocksTest#test_failing_negative_expectation: | | RSpec::Mocks::MockExpectationError: (Double (anonymous)).message(no args) | | expected: 0 times with any arguments | | received: 1 time | | | | 2) Error: | | RSpecMocksTest#test_failing_positive_expectation: | | RSpec::Mocks::MockExpectationError: (Double (anonymous)).message((any args)) | | expected: 1 time with any arguments | | received: 0 times with any arguments | | | | 3) Error: | | RSpecMocksTest#test_failing_positive_spy_expectation: | | RSpec::Mocks::MockExpectationError: (Double (anonymous)).james((any args)) | | expected: 1 time with any arguments | | received: 0 times with any arguments | | | | 4) Error: | | RSpecMocksTest#test_failing_negative_spy_expectation: | | RSpec::Mocks::MockExpectationError: (Double (anonymous)).james(no args) | | expected: 0 times with any arguments | | received: 1 time | | | | 8 runs, 0 assertions, 0 failures, 4 errors, 0 skips |