Add GraphQL::Testing::MockActionCable

guides/subscriptions/action_cable_implementation.md

@@ -10,7 +10,7 @@ index: 4
 
 [ActionCable](https://guides.rubyonrails.org/action_cable_overview.html) is a great platform for delivering GraphQL subscriptions on Rails 5+. It handles message passing (via `broadcast`) and transport (via `transmit` over a websocket).
 
-To get started, see examples in the API docs: {{ "GraphQL::Subscriptions::ActionCableSubscriptions" | api_doc }}.
+To get started, see examples in the API docs: {{ "GraphQL::Subscriptions::ActionCableSubscriptions" | api_doc }}. GraphQL-Ruby also includes a mock ActionCable implementation for testing: {{ "GraphQL::Testing::MockActionCable" | api_doc }}.
 
 See client usage for:
 

lib/graphql/subscriptions/action_cable_subscriptions.rb

@@ -81,6 +81,7 @@ class Subscriptions
     #       end
     #   end
     #
+    # @see GraphQL::Testing::MockActionCable for test helpers
     class ActionCableSubscriptions < GraphQL::Subscriptions
       SUBSCRIPTION_PREFIX = "graphql-subscription:"
       EVENT_PREFIX = "graphql-event:"

lib/graphql/testing.rb

@@ -1,2 +1,3 @@
 # frozen_string_literal: true
 require "graphql/testing/helpers"
+require "graphql/testing/mock_action_cable"

lib/graphql/testing/mock_action_cable.rb

@@ -0,0 +1,111 @@
+# frozen_string_literal: true
+module GraphQL
+  module Testing
+    # A stub implementation of ActionCable.
+    # Any methods to support the mock backend have `mock` in the name.
+    #
+    # @example Configuring your schema to use MockActionCable in the test environment
+    #   class MySchema < GraphQL::Schema
+    #     # Use MockActionCable in test:
+    #     use GraphQL::Subscriptions::ActionCableSubscriptions,
+    #       action_cable: Rails.env.test? ? GraphQL::Testing::MockActionCable : ActionCable
+    #   end
+    #
+    # @example Clearing old data before each test
+    #   setup do
+    #     GraphQL::Testing::MockActionCable.clear_mocks
+    #   end
+    #
+    # @example Using MockActionCable in a test case
+    #   # Create a channel to use in the test, pass it to GraphQL
+    #   mock_channel = GraphQL::Testing::MockActionCable.get_mock_channel
+    #   ActionCableTestSchema.execute("subscription { newsFlash { text } }", context: { channel: mock_channel })
+    #
+    #   # Trigger a subscription update
+    #   ActionCableTestSchema.subscriptions.trigger(:news_flash, {}, {text: "After yesterday's rain, someone stopped on Rio Road to help a box turtle across five lanes of traffic"})
+    #
+    #   # Check messages on the channel
+    #   expected_msg = {
+    #     result: {
+    #       "data" => {
+    #         "newsFlash" => {
+    #           "text" => "After yesterday's rain, someone stopped on Rio Road to help a box turtle across five lanes of traffic"
+    #         }
+    #       }
+    #     },
+    #     more: true,
+    #   }
+    #   assert_equal [expected_msg], mock_channel.mock_broadcasted_messages
+    #
+    class MockActionCable
+      class MockChannel
+        def initialize
+          @mock_broadcasted_messages = []
+        end
+
+        # @return [Array<Hash>] Payloads "sent" to this channel by GraphQL-Ruby
+        attr_reader :mock_broadcasted_messages
+
+        # Called by ActionCableSubscriptions. Implements a Rails API.
+        def stream_from(stream_name, coder: nil, &block)
+          # Rails uses `coder`, we don't
+          block ||= ->(msg) { @mock_broadcasted_messages << msg }
+          MockActionCable.mock_stream_for(stream_name).add_mock_channel(self, block)
+        end
+      end
+
+      # Used by mock code
+      # @api private
+      class MockStream
+        def initialize
+          @mock_channels = {}
+        end
+
+        def add_mock_channel(channel, handler)
+          @mock_channels[channel] = handler
+        end
+
+        def mock_broadcast(message)
+          @mock_channels.each do |channel, handler|
+            handler && handler.call(message)
+          end
+        end
+      end
+
+      class << self
+        # Call this before each test run to make sure that MockActionCable's data is empty
+        def clear_mocks
+          @mock_streams = {}
+        end
+
+        # Implements Rails API
+        def server
+          self
+        end
+
+        # Implements Rails API
+        def broadcast(stream_name, message)
+          stream = @mock_streams[stream_name]
+          stream && stream.mock_broadcast(message)
+        end
+
+        # Used by mock code
+        def mock_stream_for(stream_name)
+          @mock_streams[stream_name] ||= MockStream.new
+        end
+
+        # Use this as `context[:channel]` to simulate an ActionCable channel
+        #
+        # @return [GraphQL::Testing::MockActionCable::MockChannel]
+        def get_mock_channel
+          MockChannel.new
+        end
+
+        # @return [Array<String>] Streams that currently have subscribers
+        def mock_stream_names
+          @mock_streams.keys
+        end
+      end
+    end
+  end
+end

spec/graphql/subscriptions/action_cable_subscriptions_spec.rb

@@ -1,69 +1,7 @@
 # frozen_string_literal: true
 require "spec_helper"
 
-
-describe GraphQL::Subscriptions::ActionCableSubscriptions do
-  # A stub implementation of ActionCable.
-  # Any methods to support the mock backend have `mock` in the name.
-  class MockActionCable
-    class MockChannel
-      def initialize
-        @mock_broadcasted_messages = []
-      end
-
-      attr_reader :mock_broadcasted_messages
-
-      def stream_from(stream_name, coder: nil, &block)
-        # Rails uses `coder`, we don't
-        block ||= ->(msg) { @mock_broadcasted_messages << msg }
-        MockActionCable.mock_stream_for(stream_name).add_mock_channel(self, block)
-      end
-    end
-
-    class MockStream
-      def initialize
-        @mock_channels = {}
-      end
-
-      def add_mock_channel(channel, handler)
-        @mock_channels[channel] = handler
-      end
-
-      def mock_broadcast(message)
-        @mock_channels.each do |channel, handler|
-          handler && handler.call(message)
-        end
-      end
-    end
-
-    class << self
-      def clear_mocks
-        @mock_streams = {}
-      end
-
-      def server
-        self
-      end
-
-      def broadcast(stream_name, message)
-        stream = @mock_streams[stream_name]
-        stream && stream.mock_broadcast(message)
-      end
-
-      def mock_stream_for(stream_name)
-        @mock_streams[stream_name] ||= MockStream.new
-      end
-
-      def get_mock_channel
-        MockChannel.new
-      end
-
-      def mock_stream_names
-        @mock_streams.keys
-      end
-    end
-  end
-
+describe "GraphQL::Subscriptions::ActionCableSubscriptions" do
   class ActionCableTestSchema < GraphQL::Schema
     class Query < GraphQL::Schema::Object
       field :int, Integer
@@ -106,7 +44,7 @@ class Subscription < GraphQL::Schema::Object
     query(Query)
     subscription(Subscription)
     use GraphQL::Subscriptions::ActionCableSubscriptions,
-      action_cable: MockActionCable,
+      action_cable: GraphQL::Testing::MockActionCable,
       action_cable_coder: JSON
   end
 
@@ -115,20 +53,20 @@ class NamespacedActionCableTestSchema < GraphQL::Schema
     subscription(ActionCableTestSchema::Subscription)
     use GraphQL::Subscriptions::ActionCableSubscriptions,
       namespace: "other:",
-      action_cable: MockActionCable,
+      action_cable: GraphQL::Testing::MockActionCable,
       action_cable_coder: JSON
   end
 
   before do
-    MockActionCable.clear_mocks
+    GraphQL::Testing::MockActionCable.clear_mocks
   end
 
   def subscription_update(data)
     { result: { "data" => data }, more: true }
   end
 
   it "sends updates over the given `action_cable:`" do
-    mock_channel = MockActionCable.get_mock_channel
+    mock_channel = GraphQL::Testing::MockActionCable.get_mock_channel
     ActionCableTestSchema.execute("subscription { newsFlash { text } }", context: { channel: mock_channel })
     ActionCableTestSchema.subscriptions.trigger(:news_flash, {}, {text: "After yesterday's rain, someone stopped on Rio Road to help a box turtle across five lanes of traffic"})
     expected_msg = subscription_update({
@@ -140,7 +78,7 @@ def subscription_update(data)
   end
 
   it "uses arguments to divide traffic" do
-    mock_channel = MockActionCable.get_mock_channel
+    mock_channel = GraphQL::Testing::MockActionCable.get_mock_channel
     ActionCableTestSchema.execute("subscription { newsFlash(maxPerHour: 3) { text } }", context: { channel: mock_channel })
     ActionCableTestSchema.subscriptions.trigger(:news_flash, {}, {text: "Sunrise enjoyed over a cup of coffee"})
     ActionCableTestSchema.subscriptions.trigger(:news_flash, {max_per_hour: 3}, {text: "Neighbor shares bumper crop of summer squash with widow next door"})
@@ -154,7 +92,7 @@ def subscription_update(data)
   end
 
   it "handles custom argument correctly" do
-    mock_channel = MockActionCable.get_mock_channel
+    mock_channel = GraphQL::Testing::MockActionCable.get_mock_channel
     ActionCableTestSchema.execute("subscription { newsFlash(filter: { trending: true }) { text } }", context: { channel: mock_channel })
     ActionCableTestSchema.subscriptions.trigger(:news_flash, {filter: {trending: true}}, {text: "Neighbor shares bumper crop of summer squash with widow next door"})
     expected_msg = subscription_update({
@@ -166,7 +104,7 @@ def subscription_update(data)
   end
 
   it "handles nested custom argument correctly" do
-    mock_channel = MockActionCable.get_mock_channel
+    mock_channel = GraphQL::Testing::MockActionCable.get_mock_channel
     ActionCableTestSchema.execute("subscription { newsFlash(keywords: [{ value: \"rain\", fuzzy: true }]) { text } }", context: { channel: mock_channel })
     ActionCableTestSchema.subscriptions.trigger(:news_flash, {keywords: [{value: "rain", fuzzy: true}]}, {text: "After yesterday's rain, someone stopped on Rio Road to help a box turtle across five lanes of traffic"})
     expected_msg = subscription_update({
@@ -178,11 +116,11 @@ def subscription_update(data)
   end
 
   it "uses namespace to divide traffic" do
-    mock_channel_1 = MockActionCable.get_mock_channel
+    mock_channel_1 = GraphQL::Testing::MockActionCable.get_mock_channel
     ctx_1 = { channel: mock_channel_1 }
     ActionCableTestSchema.execute("subscription { newsFlash { text } }", context: ctx_1)
 
-    mock_channel_2 = MockActionCable.get_mock_channel
+    mock_channel_2 = GraphQL::Testing::MockActionCable.get_mock_channel
     ctx_2 = { channel: mock_channel_2 }
     NamespacedActionCableTestSchema.execute("subscription { newsFlash { text } }", context: ctx_2)
 
@@ -212,11 +150,11 @@ def subscription_update(data)
       "graphql-subscription:other:#{ctx_2[:subscription_id]}",
       "graphql-event:other::newsFlash:",
     ]
-    assert_equal expected_streams, MockActionCable.mock_stream_names
+    assert_equal expected_streams, GraphQL::Testing::MockActionCable.mock_stream_names
   end
 
   it "supports no_update" do
-    mock_channel = MockActionCable.get_mock_channel
+    mock_channel = GraphQL::Testing::MockActionCable.get_mock_channel
     ctx = { channel: mock_channel }
     ActionCableTestSchema.execute("subscription { evenCounter { count } }", context: ctx)
 
@@ -330,17 +268,17 @@ def self.dump(obj)
       end
 
       use GraphQL::Subscriptions::ActionCableSubscriptions,
-        action_cable: MockActionCable,
+        action_cable: GraphQL::Testing::MockActionCable,
         action_cable_coder: JSON,
         serializer: Serialize
     end
 
     it "works with multi-tenant architecture" do
-      mock_channel_1 = MockActionCable.get_mock_channel
+      mock_channel_1 = GraphQL::Testing::MockActionCable.get_mock_channel
       ctx_1 = { channel: mock_channel_1, tenant: "tenant-1" }
       MultiTenantSchema.execute("subscription { pointScored { score player { name } } }", context: ctx_1)
 
-      mock_channel_2 = MockActionCable.get_mock_channel
+      mock_channel_2 = GraphQL::Testing::MockActionCable.get_mock_channel
       ctx_2 = { channel: mock_channel_2, tenant: "tenant-2" }
       MultiTenantSchema.execute("subscription { pointScored { score player { name } } }", context: ctx_2)
       # This will use the `.find` in `def update`: