RSpec matchers and stubbing for Wisper
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README.md

Wisper::Rspec

Rspec matcher and stubbing for Wisper.

Gem Version Build Status

Installation

gem 'wisper-rspec', require: false

Usage

Broadcast Matcher

In spec_helper

require 'wisper/rspec/matchers'

RSpec::configure do |config|
  config.include(Wisper::RSpec::BroadcastMatcher)
end

In your specs:

expect { publisher.execute }.to broadcast(:an_event)

This will match both broadcast(:an_event) and broadcast(:an_event, :arg_1).

# with optional arguments
expect { publisher.execute }.to broadcast(:another_event, :arg_1, :arg_2)

With event arguments, it matches only if the event is broadcast with those arguments. This assertion matches broadcast(:another_event, :arg_1, :arg_2) but not broadcast(:another_event).

# with arguments matcher
expect { publisher.execute }.to broadcast(:event, hash_including(a: 2))

Rspec values matcher can be used to match arguments. This assertion matches broadcast(:another_event, a: 2, b: 1) but not broadcast(:another_event, a: 3)

Matchers can be composed using compound rspec matchers:

expect {
  publisher.execute(123)
  publisher.execute(234)
}.to broadcast(:event, 123).and broadcast(:event, 234)

expect {
  publisher.execute(123)
  publisher.execute(234)
}.to broadcast(:event, 123).or broadcast(:event, 234)

Note that the broadcast method is aliased as publish, similar to the Wisper library itself.

Not broadcast matcher

If you want to assert a broadcast was not made you can use not_broadcast which is especially useful when chaining expectations.

expect {
  publisher.execute(123)
}.to not_broadcast(:event, 99).and broadcast(:event, 123)

Using message expectations

If you need to assert on the listener receiving broadcast arguments you can subscribe a double with a message expectation and then use any of the argument matchers.

listener = double('Listener')

expect(listener).to receive(:an_event).with(some_args)

publisher.subscribe(listener)

publisher.execute

Stubbing publishers

You can stub publishers and their events in unit (isolated) tests that only care about reacting to events.

Given this piece of code:

class MyController
  def create
    publisher = MyPublisher.new

    publisher.on(:some_event) do |variable|
      return "Hello with #{variable}!"
    end

    publisher.execute
  end
end

You can test it like this:

require 'wisper/rspec/stub_wisper_publisher'

describe MyController do
  context "on some_event" do
    before do
      stub_wisper_publisher("MyPublisher", :execute, :some_event, "foo")
    end

    it "renders" do
      response = MyController.new.create
      expect(response).to eq "Hello with foo!"
    end
  end
end

This is useful when testing Rails controllers in isolation from the business logic.

You can use any number of args to pass to the event:

stub_wisper_publisher("MyPublisher", :execute, :some_event, "foo1", "foo2", ...)

See spec/lib/rspec_extensions_spec.rb for a runnable example.

Contributing

Yes, please.