Fix change tracking when fetching from an association collection

This requires ActiveModel 4.2+.

lib/her/model/associations/has_many_association.rb

@@ -85,7 +85,15 @@ def create(attributes = {})
         def fetch
           super.tap do |o|
             inverse_of = @opts[:inverse_of] || @parent.singularized_resource_name
-            o.each { |entry| entry.send("#{inverse_of}=", @parent) }
+
+            o.each do |entry|
+              entry.send("#{inverse_of}=", @parent)
+
+              # This fix requires ActiveModel 4.2+.
+              if entry.respond_to?(:clear_attribute_changes, true)
+                entry.send(:clear_attribute_changes, [inverse_of])
+              end
+            end
           end
         end
 

spec/model/dirty_spec.rb

@@ -7,6 +7,7 @@
       Her::API.setup url: "https://api.example.com" do |builder|
         user1 = { id: 1, fullname: "Lindsay Fünke" }
         user2 = { id: 2, fullname: "Maeby Fünke" }
+        post1 = { id: 1, user_id: 1, body: "Hello" }
 
         builder.use Her::Middleware::FirstLevelParseJSON
         builder.use Faraday::Request::UrlEncoded
@@ -18,7 +19,8 @@
           stub.put("/users/1") { [200, {}, { id: 1, fullname: "Tobias Fünke" }.to_json] }
           stub.put("/users/2") { [400, {}, { errors: ["Email cannot be blank"] }.to_json] }
           stub.post("/users")  { [200, {}, { id: 1, fullname: "Tobias Fünke" }.to_json] }
-          stub.get("/users/1/posts/1") { [200, {}, { id: 1, user_id: 1, body: "Hello" }.to_json] }
+          stub.get("/users/1/posts") { [200, {}, [post1].to_json] }
+          stub.get("/users/1/posts/1") { [200, {}, post1.to_json] }
         end
       end
 
@@ -92,6 +94,14 @@
       end
     end
 
+    context "for an existing resource from an association collection" do
+      let(:post) { Foo::User.find(1).posts.first }
+      it "has no changes" do
+        post.changes.should be_empty
+        post.should_not be_changed
+      end
+    end
+
     context "for resources from a collection" do
       let(:users) { Foo::User.all.fetch }
       it "has no changes" do