spec/graph_persistence_spec.rb in terrestrial-0.3.0 vs spec/graph_persistence_spec.rb in terrestrial-0.5.0

@@ -29,25 +29,12 @@
           email: modified_email,
         )
       )
     end
 
-    it "doesn't send associated objects to the database as columns" do
-      user.email = modified_email
-      user_store.save(user)
-
-      expect(datastore).not_to have_persisted(
-        :users,
-        hash_including(
-          posts: anything,
-        )
-      )
-    end
-
-    # TODO move to a dirty tracking spec?
-    context "when mutating entity fields in place" do
-      it "saves the object" do
+    context "when mutating an entity's fields in place" do
+      it "updates the row with new, mutated values" do
         user.email << "MUTATED"
 
         user_store.save(user)
 
         expect(datastore).to have_persisted(
@@ -108,15 +95,17 @@
 
   context "add a node to a has many association" do
     let(:new_post_attrs) {
       {
         id: "posts/neu",
+        author: nil,
         subject: "I am new",
         body: "new body",
         comments: [],
         categories: [],
         created_at: Time.now,
+        updated_at: Time.now,
       }
     }
 
     let(:new_post) {
       Post.new(new_post_attrs)
@@ -240,10 +229,51 @@
           }
         )
       end
     end
 
+    context "duplicate a node" do
+      let(:post_with_one_category) { user.posts.to_a.last }
+
+      # Spoiler alert: it does mutate the graph
+      #
+      # Feature?: The posts <=> category relationship because unique when persisted
+      # because there are no indexes on the `categories_to_posts` table making
+      # the combination of foreign keys a de facto primary key.
+      #
+      # If there was an additional primary key id field without a unique index
+      # this would not be the case.
+      #
+      # It would be nice if the collection proxy for posts <=> categories was a
+      # variant that behaved like set. Unfortunately uniqueness can only be
+      # determined by the user-defind objects' identities as the proxy would
+      # not have access to datastore ids.
+      #
+      # Mappings are available when the proxy is constructed so this is
+      # possible but awkward.
+      xit "does not mutate the graph" do
+        existing_category = post_with_one_category.categories.first
+        post_with_one_category.categories.push(existing_category)
+
+        expect(post_with_one_category.categories.map(&:id))
+          .to eq(["categories/2"])
+      end
+
+      it "does not persist the change" do
+        existing_category = post_with_one_category.categories.first
+        post_with_one_category.categories.push(existing_category)
+
+        user_store.save(user)
+
+        expect(
+          datastore[:categories_to_posts]
+            .where(:post_id => post_with_one_category.id)
+            .count
+        ).to eq(1)
+      end
+    end
+
     context "modify a node" do
       let(:category) { user.posts.first.categories.first }
       let(:modified_category_name) { "modified category" }
 
       it "mutates the graph" do
@@ -304,13 +334,15 @@
   context "when a many to one association is nil" do
     context "when the object does not have a reference to its parent" do
       it "populates that association with a nil" do
         post = Post.new(
           id: "posts/orphan",
+          author: nil,
           subject: "Nils gonna getcha",
           body: "",
           created_at: Time.parse("2015-09-05T15:00:00+01:00"),
+          updated_at: Time.parse("2015-09-05T15:00:00+01:00"),
           categories: [],
           comments: [],
         )
 
         object_store[:posts].save(post)
@@ -324,11 +356,11 @@
         )
       end
     end
 
     context "when an existing partent object reference is set to nil" do
-      it "populates that association with a nil" do
+      it "does not orphan the object and sets the foreign key according to position in the object graph" do
         comment = user
           .posts
           .flat_map(&:comments)
           .detect { |c| c.id == "comments/1" }
 
@@ -338,11 +370,11 @@
 
         expect(datastore).to have_persisted(
           :comments,
           hash_including(
             id: "comments/1",
-            commenter_id: nil,
+            commenter_id: "users/1",
           )
         )
       end
     end
   end
@@ -356,11 +388,13 @@
       begin
         user.first_name = "this will be rolled back"
         user.posts.first.subject = unpersistable_object
 
         user_store.save(user)
-      rescue Terrestrial::Error
+      rescue Object => e
       end
+
+      expect(e).to be_a(Terrestrial::Error)
 
       post_change = datastore[:users].to_a.map(&:to_a).sort
 
       expect(pre_change).to eq(post_change)
     end