Add ReferenceMockRegistry

src/spectator/mocks/mock.cr

@@ -1,5 +1,6 @@
 require "./method_call"
 require "./mocked"
+require "./reference_mock_registry"
 require "./stub"
 require "./stubbed_name"
 require "./value_stub"
@@ -51,12 +52,14 @@ module Spectator
         {{base}} ::{{type.name}}
           include ::Spectator::Mocked
 
-          @@_spectator_stubs = Hash(self, Array(::Spectator::Stub)).new do |hash, key|
-            hash[key] = [] of ::Spectator::Stub
-          end
+          {% if type.class? %}
+            @@_spectator_mock_registry = ::Spectator::ReferenceMockRegistry.new
+          {% else %}
+            {% raise "Unsupported type for injecting mock" %}
+          {% end %}
 
           private def _spectator_stubs
-            @@_spectator_stubs[self]
+            @@_spectator_mock_registry[self]
           end
 
           # Returns the mock's name formatted for user output.

src/spectator/mocks/reference_mock_registry.cr

@@ -0,0 +1,27 @@
+require "./stub"
+
+module Spectator
+  # Stores collections of stubs for mocked reference (class) types.
+  #
+  # This type is intended for all mocked reference types that have functionality "injected."
+  # That is, the type itself has mock functionality bolted on.
+  # Adding instance members should be avoided, for instance, it could mess up serialization.
+  # This registry works around that by mapping mocks (via their memory address) to a collection of stubs.
+  # Doing so prevents adding data to the mocked type.
+  class ReferenceMockRegistry
+    @object_stubs : Hash(Void*, Array(Stub))
+
+    # Creates an empty registry.
+    def initialize
+      @object_stubs = Hash(Void*, Array(Stub)).new do |hash, key|
+        hash[key] = [] of Stub
+      end
+    end
+
+    # Retrieves all stubs defined for a mocked object.
+    def [](object : Reference) : Array(Stub)
+      key = Box.box(object)
+      @object_stubs[key]
+    end
+  end
+end