Refactor Subcomponents behavior

lib/denko/behaviors/subcomponents.rb

@@ -9,18 +9,24 @@ def single_pin_components
         @single_pin_components ||= {}
       end
 
+      def hw_i2c_devs
+        @hw_i2c_devs ||= {}
+      end
+
       def add_component(component)
-        # Prevent multiple I2C::Bus instances using one physical device.
-        if component.respond_to?(:i2c_index)
-          components.each do |other_component|
-            if other_component.respond_to?(:i2c_index)
-              if component.i2c_index == other_component.i2c_index
-                raise StandardError, "I2C device index #{component.i2c_index} already in use by: #{other_component}"
-              end
-            end
-          end
-        end
+        add_single_pin(component)
+        add_hw_i2c(component)
+        components << component
+      end
+
+      def remove_component(component)
+        remove_single_pin(component)
+        remove_hw_i2c(component)
+        deleted = components.delete(component)
+        component.stop if deleted && component.respond_to?(:stop)
+      end
 
+      def add_single_pin(component)
         if component.respond_to?(:pin) && component.pin.class == Integer
           unless single_pin_components[component.pin]
             single_pin_components[component.pin] = component
@@ -29,17 +35,27 @@ def add_component(component)
                                   "already in use by: #{single_pin_components[component.pin]}"
           end
         end
+      end
 
-        components << component
+      def add_hw_i2c(component)
+        if component.respond_to?(:i2c_index)
+          unless hw_i2c_devs[component.i2c_index]
+            hw_i2c_devs[component.pin] = component
+          else
+            raise StandardError,  "Error adding #{component} to #{self}. I2C dev: #{component.i2c_index} " \
+                                  "already in use by: #{hw_i2c_devs[component.pin]}"
+          end
+        end
       end
 
-      def remove_component(component)
+      def remove_single_pin(component)
         if component.respond_to?(:pin) && component.pin.class == Integer
-          single_pin_components[component.pin] = nil
+          single_pin_components.delete(component.pin)
         end
+      end
 
-        deleted = components.delete(component)
-        component.stop if deleted && component.respond_to?(:stop)
+      def remove_hw_i2c(component)
+        hw_i2c_devs.delete(component.i2c_index) if component.respond_to?(:i2c_index)
       end
     end
   end

test/behaviors/subcomponents_test.rb

@@ -73,11 +73,21 @@ def test_calls_stop_on_remove
     mock.verify
   end
 
-  def test_stops_i2c_duplication
+  def test_disallows_duplicate_hw_i2c_buses
     i2c0 = Denko::I2C::Bus.new(board: board, pin: 0)
     assert_raises { Denko::I2C::Bus.new(board: board, pin: 1) }
+  end
 
-    i2c1 = Denko::I2C::Bus.new(board: board, pin: 2, i2c_index: 1)
+  def test_hw_i2c_buses_add_and_remove_properly
+    i2c0 = Denko::I2C::Bus.new(board: board, pin: 0, i2c_index: 0)
+    i2c1 = Denko::I2C::Bus.new(board: board, pin: 1, i2c_index: 1)
     assert_equal [i2c0, i2c1], board.components
+
+    hash = { 0 => i2c0, 1 => i2c1 }
+    assert_equal hash, board.hw_i2c_devs
+
+    board.remove_component(i2c0)
+    hash = { 1 => i2c1 }
+    assert_equal hash, board.hw_i2c_devs
   end
 end