Improve implicit description for RSpec::Rails::Matchers::ActionCable:…

…:HaveBroadcastedTo

Previously, tests defined like this:

```rb
it do
  expect { some_action }.to have_broadcasted_to("stream_name").from_channel(SomeChannel).with("some_data")
end
```

would implicitly be given the description `have broadcasted to`, which is derived from the name of the matcher method.
This didn't carry any extra information about the data we're expecting to be broadcast from the channel - behaviour
which would be very welcome in combination with Turbo Streams. With a matcher for Turbo Streams, we might benefit from
a description like "broadcast exactly 1 messages to stream with turbo-stream[action="append"][target="some_list"]".

Co-authored-by: Jon Rowe <hello@jonrowe.co.uk>
Co-authored-by: Phil Pirozhkov <pirj@users.noreply.github.com>

lib/rspec/rails/matchers/action_cable.rb

@@ -45,12 +45,17 @@ module ActionCable
       #     expect {
       #       ActionCable.server.broadcast "messages", text: 'Hi!'
       #     }.to have_broadcasted_to("messages").with(text: 'Hi!')
+      extend RSpec::Matchers::DSL
+
       def have_broadcasted_to(target = nil)
         check_action_cable_adapter
 
         ActionCable::HaveBroadcastedTo.new(target, channel: described_class)
       end
-      alias_method :broadcast_to, :have_broadcasted_to
+
+      alias_matcher :broadcast_to, :have_broadcasted_to do |desc|
+        desc.gsub("have broadcasted", "broadcast")
+      end
 
     private
 

lib/rspec/rails/matchers/action_cable/have_broadcasted_to.rb

@@ -51,6 +51,10 @@ def thrice
             exactly(:thrice)
           end
 
+          def description
+            "have broadcasted #{base_description}"
+          end
+
           def failure_message
             "expected to broadcast #{base_message}".tap do |msg|
               if @unmatching_msgs.any?
@@ -140,9 +144,14 @@ def set_expected_number(relativity, count)
               end
           end
 
-          def base_message
+          def base_description
             "#{message_expectation_modifier} #{@expected_number} messages to #{stream}".tap do |msg|
               msg << " with #{data_description(@data)}" unless @data.nil?
+            end
+          end
+
+          def base_message
+            base_description.tap do |msg|
               msg << ", but broadcast #{@matching_msgs_count}"
             end
           end
@@ -151,7 +160,7 @@ def data_description(data)
             if data.is_a?(RSpec::Matchers::Composable)
               data.description
             else
-              data
+              data.inspect
             end
           end
 

spec/rspec/rails/matchers/action_cable/have_broadcasted_to_spec.rb

@@ -226,5 +226,34 @@ def broadcast(stream, msg)
         end
       end
     end
+
+    it "has an appropriate description when not qualified with a chain method" do
+      expect(have_broadcasted_to("my_stream").description).to eq("have broadcasted exactly 1 messages to my_stream")
+    end
+
+    it "has an appropriate description when not qualified with a chain method and aliased" do
+      expect(broadcast_to("my_stream").description).to eq("broadcast exactly 1 messages to my_stream")
+    end
+
+    it "has an appropriate description when stream name is passed as an array" do
+      expect(have_broadcasted_to(%w[my_stream stream_2]).from_channel(channel).description).to eq("have broadcasted exactly 1 messages to broadcast:my_stream:stream_2")
+    end
+
+    it "has an appropriate description not mentioning the channel when qualified with `#from_channel`" do
+      expect(have_broadcasted_to("my_stream").from_channel(channel).description).to eq("have broadcasted exactly 1 messages to my_stream")
+    end
+
+    it "has an appropriate description including the expected contents when qualified with `#with`" do
+      expect(have_broadcasted_to("my_stream").from_channel(channel).with("hello world").description).to eq("have broadcasted exactly 1 messages to my_stream with \"hello world\"")
+    end
+
+    it "has an appropriate description including the matcher's description when qualified with `#with` and a composable matcher" do
+      expect(
+        have_broadcasted_to("my_stream")
+          .from_channel(channel)
+          .with(a_hash_including(a: :b))
+          .description
+      ).to eq("have broadcasted exactly 1 messages to my_stream with a hash including {:a => :b}")
+    end
   end
 end