Add tests for the issue

spec/integration/validations_spec.rb

@@ -0,0 +1,39 @@
+# rubocop:todo all
+# frozen_string_literal: true
+
+require 'spec_helper'
+require_relative './validations_spec_models'
+
+describe 'validations' do
+
+  context 'when validating presence of has_and_belongs_to_many association' do
+    let(:company) { ValidationsSpecModels::Company.create! }
+    let(:client) { ValidationsSpecModels::Client.create!(companies: [company]) }
+
+    context 'when updating the association' do
+      it 'raises an error' do
+        expect { client.update!(companies: []) }.to raise_error(Mongoid::Errors::Validations)
+      end
+
+      it 'does not persist the changes' do
+        expect { client.update!(companies: []) rescue nil }.not_to change { client.reload.companies }
+      end
+    end
+  end
+
+
+  context 'when validating presence of has_many association' do
+    let(:apartment) { ValidationsSpecModels::Apartment.create! }
+    let(:building) { ValidationsSpecModels::Building.create!(apartments: [apartment]) }
+
+    context 'when updating the association' do
+      it 'raises an error' do
+        expect { building.update!(apartments: []) }.to raise_error(Mongoid::Errors::Validations)
+      end
+
+      it 'does not persist the changes' do
+        expect { building.update!(apartments: []) rescue nil }.not_to change { building.reload.apartments }
+      end
+    end
+  end
+end

spec/integration/validations_spec_models.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module ValidationsSpecModels
+  class Company
+    include Mongoid::Document
+  end
+
+  class Client
+    include Mongoid::Document
+
+    has_and_belongs_to_many :companies, class_name: 'ValidationsSpecModels::Company'
+    validates :companies, presence: true
+  end
+
+  class Building
+    include Mongoid::Document
+    has_many :apartments, class_name: 'ValidationsSpecModels::Apartment'
+    validates :apartments, presence: true
+  end
+
+  class Apartment
+    include Mongoid::Document
+    belongs_to :building, class_name: 'ValidationsSpecModels::Building'
+  end
+end