WIP TE.

app/models/application_model/can_associations.rb

@@ -23,7 +23,6 @@ returns
       group_ids: :group_ids_access_map=
     }.each do |param, setter|
       map = params[param]
-      next if map.blank?
       next if !respond_to?(setter)
       send(setter, map)
     end

app/models/concerns/has_groups.rb

@@ -211,6 +211,7 @@ module HasGroups
   end
 
   def groups_access_map_store(map)
+    fill_group_access_buffer do
       map.each do |group_identifier, accesses|
         # use given key as identifier or look it up
         # via the given block which returns the identifier
@@ -227,19 +228,36 @@ module HasGroups
           )
         end
       end
+    end
+  end
 
+  def fill_group_access_buffer
+    @group_access_buffer = []
+    yield
     check_group_access_buffer if id
   end
 
   def push_group_access_buffer(entry)
-    @group_access_buffer ||= []
     @group_access_buffer.push(entry)
   end
 
+  def flushed_group_access_buffer
+    # group_access_buffer is at least an empty Array
+    # if changes to the map were performed
+    # otherwise it's just an update of other attributes
+    return if group_access_buffer.nil?
+    yield
+    group_access_buffer = nil
+    cache_delete
+  end
+
   def check_group_access_buffer
-    return if group_access_buffer.blank?
+
+    flushed_group_access_buffer do
       destroy_group_relations
 
+      break if group_access_buffer.blank?
+
       foreign_key = group_through.foreign_key
       entries     = group_access_buffer.collect do |entry|
         entry[foreign_key] = id
@@ -247,10 +265,8 @@ module HasGroups
       end
 
       group_through.klass.create!(entries)
+    end
 
-    group_access_buffer = nil
-
-    cache_delete
     true
   end
 

spec/models/concerns/has_groups_examples.rb

@@ -229,6 +229,19 @@ RSpec.shared_examples 'HasGroups' do
             described_class.group_through.klass.count
           }.by(3)
         end
+
+        it 'allows empty Hash value' do
+          group_access_instance.group_names_access_map = {
+            group_full.name => 'full',
+            group_read.name => %w[read change],
+          }
+
+          expect do
+            group_access_instance.group_names_access_map = {}
+          end.to change {
+            described_class.group_through.klass.count
+          }.by(-3)
+        end
       end
 
       context 'new instance' do
@@ -256,6 +269,16 @@ RSpec.shared_examples 'HasGroups' do
             described_class.group_through.klass.count
           }.by(2)
         end
+
+        it 'allows empty Hash value' do
+          expect do
+            new_group_access_instance.group_names_access_map = {}
+
+            new_group_access_instance.save
+          end.not_to change {
+            described_class.group_through.klass.count
+          }
+        end
       end
     end
 
@@ -284,6 +307,18 @@ RSpec.shared_examples 'HasGroups' do
 
         expect(group_access_instance_inactive.group_names_access_map).to be_empty
       end
+
+      it 'returns empty map if none is stored' do
+
+        group_access_instance.group_names_access_map = {
+          group_full.name => 'full',
+          group_read.name => 'read',
+        }
+
+        group_access_instance.group_names_access_map = {}
+
+        expect(group_access_instance.group_names_access_map).to be_blank
+      end
     end
 
     context '#group_ids_access_map=' do
@@ -305,7 +340,7 @@ RSpec.shared_examples 'HasGroups' do
           }.by(2)
         end
 
-        it 'stores Hash with String values' do
+        it 'stores Hash with Array<String> values' do
           expect do
             group_access_instance.group_ids_access_map = {
               group_full.id => 'full',
@@ -315,6 +350,19 @@ RSpec.shared_examples 'HasGroups' do
             described_class.group_through.klass.count
           }.by(3)
         end
+
+        it 'allows empty Hash value' do
+          group_access_instance.group_ids_access_map = {
+            group_full.id => 'full',
+            group_read.id => %w[read change],
+          }
+
+          expect do
+            group_access_instance.group_ids_access_map = {}
+          end.to change {
+            described_class.group_through.klass.count
+          }.by(-3)
+        end
       end
 
       context 'new instance' do
@@ -342,6 +390,16 @@ RSpec.shared_examples 'HasGroups' do
             described_class.group_through.klass.count
           }.by(2)
         end
+
+        it 'allows empty Hash value' do
+          expect do
+            new_group_access_instance.group_ids_access_map = {}
+
+            new_group_access_instance.save
+          end.not_to change {
+            described_class.group_through.klass.count
+          }
+        end
       end
     end
 
@@ -370,6 +428,18 @@ RSpec.shared_examples 'HasGroups' do
 
         expect(group_access_instance_inactive.group_ids_access_map).to be_empty
       end
+
+      it 'returns empty map if none is stored' do
+
+        group_access_instance.group_ids_access_map = {
+          group_full.id => 'full',
+          group_read.id => 'read',
+        }
+
+        group_access_instance.group_ids_access_map = {}
+
+        expect(group_access_instance.group_ids_access_map).to be_blank
+      end
     end
 
     context '#associations_from_param' do