fix(class_methods): define instance reader at declaration time

Moves the instance reader definition for attributes declared with
simple_class_attribute out of the singleton setter and into the
attribute declaration itself.

Earlier behavior: the instance method (e.g., flag) was defined only when
the class setter (klass.flag = ...) ran. That caused instances to lack
the reader method until the setter had been called.

New behavior: when simple_class_attribute :name is declared, the
instance reader name is defined immediately (but it still checks an
instance ivar first and falls back to the singleton-class value if the
ivar isn't set). The class setter now only defines the singleton reader
to return the assigned value.

Why?:

Fixes a NoMethodError in the failing spec where an instance reader is
expected to exist even if the class-level setter hasn't been used yet
(for example, the test that sets instance.instance_variable_set('@Flag',
'local') and expects instance.flag to return 'local').

Behavior is preserved: instance-level overrides still take precedence
(instance ivar wins), and setting the instance ivar does not change the
singleton class value.

Author: julitrows

lib/injectable/class_methods.rb

@@ -28,22 +28,26 @@ def simple_class_attribute(*attrs)
 
         ivar = "@#{name}"
 
+        # Define the instance reader immediately when this attribute is declared
+        # so instances always respond to the reader even if the singleton
+        # class value has not been set yet.
+        if singleton_class?
+          class_eval do
+            define_method(name) do
+              if instance_variable_defined? ivar
+                instance_variable_get ivar
+              else
+                singleton_class.send name
+              end
+            end
+          end
+        end
+
         define_singleton_method("#{name}=") do |val|
           singleton_class.class_eval do
             define_method(name) { val }
           end
 
-          if singleton_class?
-            class_eval do
-              define_method(name) do
-                if instance_variable_defined? ivar
-                  instance_variable_get ivar
-                else
-                  singleton_class.send name
-                end
-              end
-            end
-          end
           val
         end
       end

spec/injectable/class_methods_spec.rb

@@ -29,7 +29,7 @@ def call
       expect(instance.flag).to eq('on')
     end
 
-    it 'allows to modify attribute value on the instance', skip: 'Failing, need to investigate' do
+    it 'allows to modify attribute value on the instance' do
       instance = klass.new
       instance.instance_variable_set('@flag', 'local')
       expect(instance.flag).to eq('local')