Store removal information

app/models/concerns/ignorable_columns.rb

@@ -11,8 +11,18 @@ module IgnorableColumns
       raise ArgumentError, 'Please indicate when we can stop ignoring columns with remove_after, example: ignore_columns(:name, remove_after: \'2019-12-01\', remove_with: \'12.6\')' unless remove_after && remove_with
 
       self.ignored_columns += columns.flatten
+
+      @ignored_columns_details ||= {}
+
+      columns.flatten.each do |column|
+        @ignored_columns_details[column] = { remove_after: remove_after, remove_with: remove_with }
+      end
     end
 
     alias_method :ignore_column, :ignore_columns
+
+    def ignored_columns_details
+      @ignored_columns_details || {}
+    end
   end
 end

spec/models/concerns/ignorable_columns_spec.rb

@@ -31,4 +31,22 @@ describe IgnorableColumns do
     expect { subject.ignore_columns(:name, remove_after: '2019-12-01', remove_with: nil) }.to raise_error(ArgumentError, /Please indicate/)
   end
 
+  describe '.ignored_columns_details' do
+    it 'stores removal information' do
+      subject.ignore_column(:name, remove_after: '2019-12-01', remove_with: '12.6')
+
+      expect(subject.ignored_columns_details[:name]).to eq(remove_after: '2019-12-01', remove_with: '12.6')
+    end
+
+    it 'stores removal information (array version)' do
+      subject.ignore_column(%i[name created_at], remove_after: '2019-12-01', remove_with: '12.6')
+
+      expect(subject.ignored_columns_details[:name]).to eq(remove_after: '2019-12-01', remove_with: '12.6')
+      expect(subject.ignored_columns_details[:created_at]).to eq(remove_after: '2019-12-01', remove_with: '12.6')
+    end
+
+    it 'defaults to empty Hash' do
+      expect(subject.ignored_columns_details).to eq({})
+    end
+  end
 end