Add group <> project level MR approval settings cascade

Adds a new API endpoint to be the canonical list of
MR approval settings for a project, which inherits
from the instance and group. It also contains
information about which level defined the rule.

Adds logic to the Resovler class to calculate.

Adds specs for every concievable input.

ee/app/policies/ee/project_policy.rb

@@ -32,6 +32,10 @@ module EE
           ::Gitlab::CurrentSettings.disable_overriding_approvers_per_merge_request
       end
 
+      condition(:group_merge_request_approval_settings_enabled) do
+        @subject.feature_available?(:group_merge_request_approval_settings)
+      end
+
       with_scope :global
       condition(:locked_merge_request_author_setting) do
         License.feature_available?(:admin_merge_request_approvers_rules) &&
@@ -387,6 +391,10 @@ module EE
       end
 
       rule { auditor | can?(:developer_access) }.enable :add_project_to_instance_security_dashboard
+
+      rule { (admin | owner) & group_merge_request_approval_settings_enabled }.policy do
+        enable :admin_merge_request_approval_settings
+      end
     end
 
     override :lookup_access_level!

ee/app/services/merge_request_approval_settings/update_service.rb

@@ -5,13 +5,30 @@ module MergeRequestApprovalSettings
     def execute
       return ServiceResponse.error(message: 'Insufficient permissions') unless allowed?
 
-      setting = GroupMergeRequestApprovalSetting.find_or_initialize_by_group(container)
-      setting.assign_attributes(params)
+      if container.is_a?(Group)
+        setting = GroupMergeRequestApprovalSetting.find_or_initialize_by_group(container)
+        setting.assign_attributes(params)
 
-      if setting.save
-        ServiceResponse.success(payload: setting)
-      else
-        ServiceResponse.error(message: setting.errors.messages)
+        if setting.save
+          ServiceResponse.success(payload: setting)
+        else
+          ServiceResponse.error(message: setting.errors.messages)
+        end
+      elsif container.is_a?(Project)
+        resolved_params = {
+          merge_requests_author_approval: params[:allow_author_approval],
+          merge_requests_disable_committers_approval: !params[:allow_committer_approval],
+          disable_overriding_approvers_per_merge_request: !params[:allow_overrides_to_approver_list_per_merge_request],
+          reset_approvals_on_push: !params[:retain_approvals_on_push],
+          require_password_to_approve: params[:require_password_to_approve]
+        }
+        result = ::Projects::UpdateService.new(container, current_user, resolved_params).execute
+
+        if result[:status] == :success
+          ServiceResponse.success(payload: container)
+        else
+          ServiceResponse.error(message: container.errors.messages)
+        end
       end
     end
 

ee/lib/api/entities/group_merge_request_approval_setting.rb → ee/lib/api/entities/merge_request_approval_setting.rb

@@ -2,7 +2,7 @@
 
 module API
   module Entities
-    class GroupMergeRequestApprovalSetting < Grape::Entity
+    class MergeRequestApprovalSetting < Grape::Entity
       expose :allow_author_approval
       expose :allow_committer_approval
       expose :allow_overrides_to_approver_list_per_merge_request

ee/lib/api/group_merge_request_approval_settings.rb

-# frozen_string_literal: true
-
-module API
-  class GroupMergeRequestApprovalSettings < ::API::Base
-    feature_category :source_code_management
-
-    before do
-      authenticate!
-      not_found! unless ::Feature.enabled?(:group_merge_request_approval_settings_feature_flag, user_group)
-
-      authorize! :admin_merge_request_approval_settings, user_group
-    end
-
-    params do
-      requires :id, type: String, desc: 'The ID of a group'
-    end
-    resource :groups, requirements: ::API::API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
-      segment ':id/merge_request_approval_setting' do
-        desc 'Get group merge request approval setting' do
-          detail 'This feature is gated by the :group_merge_request_approval_settings_feature_flag'
-          success ::API::Entities::GroupMergeRequestApprovalSetting
-        end
-        get do
-          setting = ComplianceManagement::MergeRequestApprovalSettings::Resolver.new(user_group).execute
-
-          present setting, with: ::API::Entities::GroupMergeRequestApprovalSetting
-        end
-
-        desc 'Update existing merge request approval setting' do
-          detail 'This feature is gated by the :group_merge_request_approval_settings_feature_flag'
-          success ::API::Entities::GroupMergeRequestApprovalSetting
-        end
-        params do
-          optional :allow_author_approval, type: Boolean, desc: 'Allow authors to self-approve merge requests'
-          optional :allow_committer_approval, type: Boolean, desc: 'Allow committers to approve merge requests'
-          optional :allow_overrides_to_approver_list_per_merge_request,
-                   type: Boolean, desc: 'Allow overrides to approver list per merge request'
-          optional :retain_approvals_on_push, type: Boolean, desc: 'Retain approval count on a new push'
-          optional :require_password_to_approve,
-                   type: Boolean, desc: 'Require approver to authenticate before approving'
-
-          at_least_one_of :allow_author_approval,
-                          :allow_committer_approval,
-                          :allow_overrides_to_approver_list_per_merge_request,
-                          :retain_approvals_on_push,
-                          :require_password_to_approve
-        end
-        put do
-          setting_params = declared_params(include_missing: false)
-
-          response = ::MergeRequestApprovalSettings::UpdateService
-            .new(container: user_group, current_user: current_user, params: setting_params).execute
-
-          if response.success?
-            setting = ComplianceManagement::MergeRequestApprovalSettings::Resolver.new(user_group).execute
-
-            present setting, with: ::API::Entities::GroupMergeRequestApprovalSetting
-          else
-            render_api_error!(response.message, :bad_request)
-          end
-        end
-      end
-    end
-  end
-end

ee/lib/api/merge_request_approval_settings.rb

+# frozen_string_literal: true
+
+module API
+  class MergeRequestApprovalSettings < ::API::Base
+    feature_category :source_code_management
+
+    before do
+      authenticate!
+    end
+
+    helpers do
+      params :merge_request_approval_settings do
+        optional :allow_author_approval, type: Boolean, desc: 'Allow authors to self-approve merge requests', allow_blank: false
+        optional :allow_committer_approval, type: Boolean, desc: 'Allow committers to approve merge requests', allow_blank: false
+        optional :allow_overrides_to_approver_list_per_merge_request,
+                 type: Boolean, desc: 'Allow overrides to approver list per merge request', allow_blank: false
+        optional :retain_approvals_on_push, type: Boolean, desc: 'Retain approval count on a new push', allow_blank: false
+        optional :require_password_to_approve,
+                 type: Boolean, desc: 'Require approver to authenticate before approving', allow_blank: false
+
+        at_least_one_of :allow_author_approval,
+                        :allow_committer_approval,
+                        :allow_overrides_to_approver_list_per_merge_request,
+                        :retain_approvals_on_push,
+                        :require_password_to_approve
+      end
+    end
+
+    params do
+      requires :id, type: String, desc: 'The ID of a project'
+    end
+    resource :projects, requirements: ::API::API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
+      before do
+        authorize! :admin_merge_request_approval_settings, user_project
+      end
+      segment ':id/merge_request_approval_setting' do
+        desc 'Get project-level MR approval settings' do
+          detail 'This feature was introduced in 14.3 behind the :group_merge_request_approval_settings_feature_flag'
+          success EE::API::Entities::MergeRequestApprovalSettings
+        end
+        get do
+          not_found! unless ::Feature.enabled?(:group_merge_request_approval_settings_feature_flag, user_project.root_ancestor)
+
+          group = user_project.group.present? ? user_project.root_ancestor : nil
+          setting = ComplianceManagement::MergeRequestApprovalSettings::Resolver.new(group, project: user_project).execute
+
+          present setting, with: ::API::Entities::MergeRequestApprovalSetting
+        end
+        desc 'Update existing merge request approval setting' do
+          detail 'This feature is gated by the :group_merge_request_approval_settings_feature_flag'
+          success ::API::Entities::MergeRequestApprovalSetting
+        end
+        params do
+          use :merge_request_approval_settings
+        end
+        put do
+          setting_params = declared_params(include_missing: false)
+
+          response = ::MergeRequestApprovalSettings::UpdateService
+                       .new(container: user_project, current_user: current_user, params: setting_params).execute
+
+          if response.success?
+            group = user_project.group.present? ? user_project.root_ancestor : nil
+
+            setting = ComplianceManagement::MergeRequestApprovalSettings::Resolver.new(group, project: user_project).execute
+
+            present setting, with: ::API::Entities::MergeRequestApprovalSetting
+          else
+            render_api_error!(response.message, :bad_request)
+          end
+        end
+      end
+    end
+
+    params do
+      requires :id, type: String, desc: 'The ID of a group'
+    end
+    resource :groups, requirements: ::API::API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
+      before do
+        not_found! unless ::Feature.enabled?(:group_merge_request_approval_settings_feature_flag, user_group)
+
+        authorize! :admin_merge_request_approval_settings, user_group
+      end
+      segment ':id/merge_request_approval_setting' do
+        desc 'Get group merge request approval setting' do
+          detail 'This feature is gated by the :group_merge_request_approval_settings_feature_flag'
+          success ::API::Entities::MergeRequestApprovalSetting
+        end
+        get do
+          setting = ComplianceManagement::MergeRequestApprovalSettings::Resolver.new(user_group).execute
+
+          present setting, with: ::API::Entities::MergeRequestApprovalSetting
+        end
+
+        desc 'Update existing merge request approval setting' do
+          detail 'This feature is gated by the :group_merge_request_approval_settings_feature_flag'
+          success ::API::Entities::MergeRequestApprovalSetting
+        end
+        params do
+          use :merge_request_approval_settings
+        end
+        put do
+          setting_params = declared_params(include_missing: false)
+
+          response = ::MergeRequestApprovalSettings::UpdateService
+            .new(container: user_group, current_user: current_user, params: setting_params).execute
+
+          if response.success?
+            setting = ComplianceManagement::MergeRequestApprovalSettings::Resolver.new(user_group).execute
+
+            present setting, with: ::API::Entities::MergeRequestApprovalSetting
+          else
+            render_api_error!(response.message, :bad_request)
+          end
+        end
+      end
+    end
+  end
+end

ee/lib/compliance_management/merge_request_approval_settings/resolver.rb

@@ -2,8 +2,9 @@
 module ComplianceManagement
   module MergeRequestApprovalSettings
     class Resolver
-      def initialize(group)
+      def initialize(group, project: nil)
         @group = group
+        @project = project
       end
 
       def execute
@@ -17,38 +18,45 @@ module ComplianceManagement
       end
 
       def allow_author_approval
-        instance_value = instance_settings.current_application_settings.prevent_merge_requests_author_approval
+        instance_value = !instance_settings.prevent_merge_requests_author_approval
         group_value = group_settings&.allow_author_approval
+        project_value = @project&.merge_requests_author_approval
 
-        setting(:allow_author_approval, instance_value, group_value, default: true)
+        setting(instance_value, group_value, project_value)
       end
 
       def allow_committer_approval
-        instance_value = instance_settings.prevent_merge_requests_committers_approval
+        instance_value = !instance_settings.prevent_merge_requests_committers_approval
         group_value = group_settings&.allow_committer_approval
+        project_value = @project ? !@project.merge_requests_disable_committers_approval : nil
 
-        setting(:allow_committer_approval, instance_value, group_value, default: true)
+        setting(instance_value, group_value, project_value)
       end
 
       def allow_overrides_to_approver_list_per_merge_request
-        instance_value = instance_settings.disable_overriding_approvers_per_merge_request
+        instance_value = !instance_settings.disable_overriding_approvers_per_merge_request
         group_value = group_settings&.allow_overrides_to_approver_list_per_merge_request
+        project_value = @project ? !@project.disable_overriding_approvers_per_merge_request : nil
 
-        setting(:allow_overrides_to_approver_list_per_merge_request, instance_value, group_value, default: true)
+        setting(instance_value, group_value, project_value)
       end
 
       def retain_approvals_on_push
-        instance_value = nil
         group_value = group_settings&.retain_approvals_on_push
+        project_value = @project ? !@project.reset_approvals_on_push : nil
 
-        setting(:retain_approvals_on_push, instance_value, group_value, default: true)
+        setting(nil, group_value, project_value)
       end
 
       def require_password_to_approve
-        instance_value = nil
         group_value = group_settings&.require_password_to_approve
+        project_value = @project&.require_password_to_approve
 
-        setting(:require_password_to_approve, instance_value, group_value, default: false)
+        ComplianceManagement::MergeRequestApprovalSettings::Setting.new(
+          value: require_password_value(group_value, project_value),
+          locked: require_password_locked?(group_value, false),
+          inherited_from: (:group if require_password_locked?(group_value, false))
+        )
       end
 
       private
@@ -61,16 +69,39 @@ module ComplianceManagement
         @group&.group_merge_request_approval_setting
       end
 
-      def setting(name, instance_value, group_value, default:)
-        # Setting value should be the instance-level, if set.
-        # Otherwise group-level.
-        # Finally, fallback on to the default defined here.
-        value = instance_value ? !instance_value : group_value
+      def value(instance_value, group_value, project_value)
+        [instance_value, group_value, project_value].compact.all?
+      end
+
+      def require_password_value(group_value, project_value)
+        [group_value, project_value].any?
+      end
+
+      def locked?(instance_value, group_value, project_value)
+        _, *inherited = [project_value, group_value, instance_value].compact
+
+        inherited.any? { |value| value == false }
+      end
+
+      def require_password_locked?(group_value, default)
+        return false if @project.nil?
+        return false if @group.nil?
+
+        group_value || default
+      end
+
+      def inherited_from(instance_value, group_value, project_value)
+        return :instance if instance_value == false
+        return :group if group_value == false && !project_value.nil?
+
+        nil
+      end
 
+      def setting(instance_value, group_value, project_value)
         ComplianceManagement::MergeRequestApprovalSettings::Setting.new(
-          value: value.nil? ? default : value,
-          locked: instance_value.nil? ? false : instance_value,
-          inherited_from: instance_value ? :instance : nil
+          value: value(instance_value, group_value, project_value),
+          locked: locked?(instance_value, group_value, project_value),
+          inherited_from: inherited_from(instance_value, group_value, project_value)
         )
       end
     end

ee/lib/ee/api/api.rb

@@ -30,7 +30,7 @@ module EE
         mount ::API::GroupPushRule
         mount ::API::MergeTrains
         mount ::API::GroupHooks
-        mount ::API::GroupMergeRequestApprovalSettings
+        mount ::API::MergeRequestApprovalSettings
         mount ::API::Scim
         mount ::API::ManagedLicenses
         mount ::API::ProjectApprovals

ee/spec/lib/api/entities/group_merge_request_approval_setting_spec.rb → ee/spec/lib/api/entities/merge_request_approval_setting_spec.rb

@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-RSpec.describe API::Entities::GroupMergeRequestApprovalSetting do
+RSpec.describe API::Entities::MergeRequestApprovalSetting do
   let(:group_merge_request_approval_setting) { build(:group_merge_request_approval_setting) }
 
   subject { described_class.new(group_merge_request_approval_setting).as_json }

ee/spec/lib/compliance_management/merge_request_approval_settings/resolver_spec.rb

@@ -7,6 +7,9 @@ RSpec.describe ::ComplianceManagement::MergeRequestApprovalSettings::Resolver do
 
   let_it_be(:group) { create(:group) }
 
+  let(:project) { build(:project, group: group) }
+  let(:namespace_project) { build(:project) }
+
   before(:all) do
     group.create_group_merge_request_approval_setting
   end
@@ -17,93 +20,208 @@ RSpec.describe ::ComplianceManagement::MergeRequestApprovalSettings::Resolver do
     expect(resolver).not_to be_nil
   end
 
-  shared_examples 'resolvable but has no instance setting' do
-    where(:group_allows_approval, :value, :locked, :inherited_from) do
-      true  | true  | false | nil
-      false | false | false | nil
+  shared_examples 'a MR approval setting' do
+    it 'has the correct value' do
+      expect(object.value).to eq(value)
     end
 
-    with_them do
-      before do
-        group.group_merge_request_approval_setting.update!(instance_method => group_allows_approval)
-      end
+    it 'has the correct locked status' do
+      expect(object.locked).to eq(locked)
+    end
 
-      let(:object) { described_class.new(group).send(instance_method) }
+    it 'has the correct inheritance' do
+      expect(object.inherited_from).to eq(inherited_from)
+    end
+  end
 
-      it 'has the correct value' do
-        expect(object.value).to eq(value)
-      end
+  describe '#allow_author_approval' do
+    where(:instance_prevents_approval, :group_allows_approval, :project_allows_approval, :value, :locked, :inherited_from) do
+      # Cases where the project is nil
+      true  | true  | nil | false | true  | :instance
+      true  | false | nil | false | true  | :instance
+      false | true  | nil | true  | false | nil
+      false | false | nil | false | false | nil
+
+      # Cases which do not include a group
+      false | nil | true  | true  | false | nil
+      false | nil | false | false | false | nil
+      true  | nil | false | false | true  | :instance
+
+      # Cases which include a project
+      false | true  | true  | true  | false | nil
+      false | false | true  | false | true  | :group
+      true  | true  | true  | false | true  | :instance
+      false | true  | false | false | false | nil
+    end
 
-      it 'has the correct locked status' do
-        expect(object.locked).to eq(locked)
+    with_them do
+      before do
+        stub_ee_application_setting(prevent_merge_requests_author_approval: instance_prevents_approval)
+        group.group_merge_request_approval_setting.update!(allow_author_approval: !!group_allows_approval)
+        project.update!(merge_requests_author_approval: project_allows_approval)
       end
 
-      it 'has the correct inheritance' do
-        expect(object.inherited_from).to eq(inherited_from)
+      let(:object) do
+        if project_allows_approval.nil?
+          described_class.new(group).allow_author_approval
+        elsif group_allows_approval.nil?
+          described_class.new(nil, project: project).allow_author_approval
+        else
+          described_class.new(group, project: project).allow_author_approval
+        end
       end
+
+      it_behaves_like 'a MR approval setting'
     end
   end
 
-  shared_examples 'resolvable' do
-    where(:instance_prevents_approval, :group_allows_approval, :value, :locked, :inherited_from) do
-      true  | true  | false | true  | :instance
-      true  | false | false | true  | :instance
-      false | true  | true  | false | nil
-      false | false | false | false | nil
+  describe '#allow_committer_approval' do
+    where(:instance_prevents_approval, :group_allows_approval, :project_prevents_approval, :value, :locked, :inherited_from) do
+      # Cases where the project is nil
+      true  | true  | nil | false | true  | :instance
+      true  | false | nil | false | true  | :instance
+      false | true  | nil | true  | false | nil
+      false | false | nil | false | false | nil
+
+      # Cases which do not include a group
+      false | nil | true  | false | false | nil
+      true  | nil | false | false | true  | :instance
+
+      # Cases which include a project
+      false | true  | true  | false | false | nil
+      false | false | false | false | true  | :group
+      true  | true  | false | false | true  | :instance
     end
 
     with_them do
       before do
-        stub_ee_application_setting(instance_flag => instance_prevents_approval)
-        group.group_merge_request_approval_setting.update!(group_flag => group_allows_approval)
+        stub_ee_application_setting(prevent_merge_requests_committers_approval: instance_prevents_approval)
+        group.group_merge_request_approval_setting.update!(allow_committer_approval: !!group_allows_approval)
+        project.update!(merge_requests_disable_committers_approval: project_prevents_approval)
       end
 
-      let(:object) { described_class.new(group).send(group_flag) }
-
-      it 'has the correct value' do
-        expect(object.value).to eq(value)
+      let(:object) do
+        if project_prevents_approval.nil?
+          described_class.new(group).allow_committer_approval
+        elsif group_allows_approval.nil?
+          described_class.new(nil, project: project).allow_committer_approval
+        else
+          described_class.new(group, project: project).allow_committer_approval
+        end
       end
 
-      it 'has the correct locked status' do
-        expect(object.locked).to eq(locked)
+      it_behaves_like 'a MR approval setting'
+    end
+  end
+
+  describe '#allow_overrides_to_approver_list_per_merge_request' do
+    where(:instance_prevents_approval, :group_allows_approval, :project_prevents_approval, :value, :locked, :inherited_from) do
+      # Cases where the project is nil
+      true  | true  | nil | false | true  | :instance
+      true  | false | nil | false | true  | :instance
+      false | true  | nil | true  | false | nil
+      false | false | nil | false | false | nil
+
+      # Cases which do not include a group
+      false | nil | true  | false | false | nil
+      true  | nil | false | false | true  | :instance
+
+      # Cases which include a project
+      false | true  | true  | false | false | nil
+      false | false | false | false | true  | :group
+      true  | true  | false | false | true  | :instance
+    end
+
+    with_them do
+      before do
+        stub_ee_application_setting(disable_overriding_approvers_per_merge_request: instance_prevents_approval)
+        group.group_merge_request_approval_setting.update!(allow_overrides_to_approver_list_per_merge_request: !!group_allows_approval)
+        project.update!(disable_overriding_approvers_per_merge_request: project_prevents_approval)
       end
 
-      it 'has the correct inheritance' do
-        expect(object.inherited_from).to eq(inherited_from)
+      let(:object) do
+        if project_prevents_approval.nil?
+          described_class.new(group).allow_overrides_to_approver_list_per_merge_request
+        elsif group_allows_approval.nil?
+          described_class.new(nil, project: project).allow_overrides_to_approver_list_per_merge_request
+        else
+          described_class.new(group, project: project).allow_overrides_to_approver_list_per_merge_request
+        end
       end
+
+      it_behaves_like 'a MR approval setting'
     end
   end
 
-  describe '#allow_author_approval' do
-    let(:instance_flag) { :prevent_merge_requests_author_approval }
-    let(:group_flag) { :allow_author_approval }
+  describe '#retain_approvals_on_push' do
+    where(:group_retains_approvals, :project_resets_approvals, :value, :locked, :inherited_from) do
+      true  | nil | true  | false | nil
+      false | nil | false | false | nil
+
+      # Cases which do not include a group
+      nil | true  | false | false | nil
+      nil | false | true  | false | nil
+
+      # Cases with a project
+      true  | false | true  | false | nil
+      false | true  | false | true  | :group
+      false | false | false | true  | :group
+      true  | true  | false | false | nil
+    end
 
-    it_behaves_like 'resolvable'
-  end
+    with_them do
+      before do
+        group.group_merge_request_approval_setting.update!(retain_approvals_on_push: !!group_retains_approvals)
+        project.update!(reset_approvals_on_push: project_resets_approvals)
+      end
 
-  describe '#allow_committer_approval' do
-    let(:instance_flag) { :prevent_merge_requests_committers_approval }
-    let(:group_flag) { :allow_committer_approval }
+      let(:object) do
+        if project_resets_approvals.nil?
+          described_class.new(group).retain_approvals_on_push
+        elsif group_retains_approvals.nil?
+          described_class.new(nil, project: project).retain_approvals_on_push
+        else
+          described_class.new(group, project: project).retain_approvals_on_push
+        end
+      end
 
-    it_behaves_like 'resolvable'
+      it_behaves_like 'a MR approval setting'
+    end
   end
 
-  describe '#allow_overrides_to_approver_list_per_merge_request' do
-    let(:instance_flag) { :disable_overriding_approvers_per_merge_request }
-    let(:group_flag) { :allow_overrides_to_approver_list_per_merge_request }
+  describe '#require_password_to_approve' do
+    where(:group_requires_password, :project_requires_password, :value, :locked, :inherited_from) do
+      true  | nil | true  | false | nil
+      false | nil | false | false | nil
 
-    it_behaves_like 'resolvable'
-  end
+      # Cases which do not include a group
+      nil | true  | true  | false | nil
+      nil | false | false | false | nil
 
-  describe '#retain_approvals_on_push' do
-    let(:instance_method) { :retain_approvals_on_push }
+      # Cases with a project
+      true  | false | true  | true  | :group
+      true  | true  | true  | true  | :group
+      false | false | false | false | nil
+      false | true  | true  | false | nil
+    end
 
-    it_behaves_like 'resolvable but has no instance setting'
-  end
+    with_them do
+      before do
+        group.group_merge_request_approval_setting.update!(require_password_to_approve: !!group_requires_password)
+        project.update!(require_password_to_approve: project_requires_password)
+      end
 
-  describe '#require_password_to_approve' do
-    let(:instance_method) { :require_password_to_approve }
+      let(:object) do
+        if project_requires_password.nil?
+          described_class.new(group).require_password_to_approve
+        elsif group_requires_password.nil?
+          described_class.new(nil, project: project).require_password_to_approve
+        else
+          described_class.new(group, project: project).require_password_to_approve
+        end
+      end
 
-    it_behaves_like 'resolvable but has no instance setting'
+      it_behaves_like 'a MR approval setting'
+    end
   end
 end

ee/spec/policies/project_policy_spec.rb

@@ -1404,6 +1404,35 @@ RSpec.describe ProjectPolicy do
     end
   end
 
+  describe ':admin_merge_request_approval_settings' do
+    let(:project) { private_project }
+
+    using RSpec::Parameterized::TableSyntax
+
+    where(:role, :licensed, :allowed) do
+      :guest      | true  | false
+      :reporter   | true  | false
+      :developer  | true  | false
+      :maintainer | false | false
+      :maintainer | true  | false
+      :owner      | false | false
+      :owner      | true  | true
+      :admin      | true  | true
+      :admin      | false | false
+    end
+
+    with_them do
+      let(:current_user) { public_send(role) }
+
+      before do
+        stub_licensed_features(group_merge_request_approval_settings: licensed)
+        enable_admin_mode!(current_user) if role == :admin
+      end
+
+      it { is_expected.to(allowed ? be_allowed(:admin_merge_request_approval_settings) : be_disallowed(:admin_merge_request_approval_settings)) }
+    end
+  end
+
   describe ':modify_approvers_rules' do
     it_behaves_like 'merge request approval settings' do
       let(:app_setting) { :disable_overriding_approvers_per_merge_request }

ee/spec/requests/api/group_merge_request_approval_settings_spec.rb → ee/spec/requests/api/merge_request_approval_settings_spec.rb

@@ -2,13 +2,12 @@
 
 require 'spec_helper'
 
-RSpec.describe API::GroupMergeRequestApprovalSettings do
+RSpec.describe API::MergeRequestApprovalSettings do
   let_it_be_with_reload(:group) { create(:group) }
   let_it_be(:user) { create(:user) }
+  let_it_be_with_reload(:project) { create(:project, group: group) }
   let_it_be(:setting) { create(:group_merge_request_approval_setting, group: group) }
 
-  let(:url) { "/groups/#{group.id}/merge_request_approval_setting" }
-
   shared_examples "resolvable" do
     using RSpec::Parameterized::TableSyntax
 
@@ -44,6 +43,8 @@ RSpec.describe API::GroupMergeRequestApprovalSettings do
   end
 
   describe 'GET /groups/:id/merge_request_approval_settings' do
+    let(:url) { "/groups/#{group.id}/merge_request_approval_setting" }
+
     context 'when feature flag is disabled' do
       before do
         stub_feature_flags(group_merge_request_approval_settings_feature_flag: false)
@@ -131,6 +132,7 @@ RSpec.describe API::GroupMergeRequestApprovalSettings do
   end
 
   describe 'PUT /groups/:id/merge_request_approval_setting' do
+    let(:url) { "/groups/#{group.id}/merge_request_approval_setting" }
     let(:params) { { allow_author_approval: true } }
 
     context 'when feature flag is disabled' do
@@ -172,13 +174,13 @@ RSpec.describe API::GroupMergeRequestApprovalSettings do
         end
 
         context 'when update fails' do
-          let(:params) { { allow_author_approval: nil } }
+          let(:params) { { allow_author_approval: 45 } }
 
           it 'returns 400 status', :aggregate_failures do
             put api(url, user), params: params
 
             expect(response).to have_gitlab_http_status(:bad_request)
-            expect(json_response['message']).to eq('allow_author_approval' => ['must be a boolean value'])
+            expect(json_response['error']).to match(/allow_.*_approval is invalid/)
           end
         end
 
@@ -209,4 +211,99 @@ RSpec.describe API::GroupMergeRequestApprovalSettings do
       end
     end
   end
+
+  describe 'GET /projects/:id/merge_request_approval_settings' do
+    let(:url) { "/projects/#{project.id}/merge_request_approval_setting" }
+
+    context 'when feature flag is disabled' do
+      before do
+        stub_feature_flags(group_merge_request_approval_settings_feature_flag: false)
+      end
+
+      it 'returns 404 status' do
+        get api(url, user)
+
+        expect(response).to have_gitlab_http_status(:not_found)
+      end
+    end
+
+    context 'when feature flag is enabled' do
+      before do
+        group.add_owner(user)
+        allow(Ability).to receive(:allowed?).and_call_original
+        stub_feature_flags(group_merge_request_approval_settings_feature_flag: true)
+        stub_licensed_features(group_merge_request_approval_settings: true)
+        allow(Ability).to receive(:allowed?)
+                            .with(user, :admin_merge_request_approval_settings, project)
+                            .and_return(true)
+      end
+
+      it 'matches the response schema' do
+        get api(url, user)
+
+        expect(response).to match_response_schema('public_api/v4/group_merge_request_approval_settings', dir: 'ee')
+      end
+
+      context 'when the project does not have existing settings' do
+        before do
+          project.update!(
+            merge_requests_author_approval: nil,
+            merge_requests_disable_committers_approval: nil,
+            disable_overriding_approvers_per_merge_request: nil,
+            reset_approvals_on_push: nil,
+            require_password_to_approve: nil
+          )
+        end
+
+        it 'returns in-memory default settings', :aggregate_failures do
+          get api(url, user)
+
+          expect(response).to have_gitlab_http_status(:ok)
+          expect(json_response['allow_author_approval']['value']).to eq(false)
+          expect(json_response['allow_committer_approval']['value']).to eq(false)
+          expect(json_response['allow_overrides_to_approver_list_per_merge_request']['value']).to eq(false)
+          expect(json_response['retain_approvals_on_push']['value']).to eq(false)
+          expect(json_response['require_password_to_approve']['value']).to eq(false)
+        end
+      end
+    end
+  end
+
+  describe 'PUT /projects/:id/merge_request_approval_settings' do
+    let(:url) { "/projects/#{project.id}/merge_request_approval_setting" }
+
+    context 'when feature flag is disabled' do
+      before do
+        stub_feature_flags(group_merge_request_approval_settings_feature_flag: false)
+      end
+
+      it 'returns 404 status' do
+        put api(url, user)
+
+        expect(response).to have_gitlab_http_status(:not_found)
+      end
+    end
+
+    context 'when feature flag is enabled' do
+      let(:params) { { retain_approvals_on_push: false } }
+
+      before do
+        group.add_owner(user)
+        allow(Ability).to receive(:allowed?).and_call_original
+        stub_feature_flags(group_merge_request_approval_settings_feature_flag: true)
+        stub_licensed_features(group_merge_request_approval_settings: true)
+        allow(Ability).to receive(:allowed?)
+                            .with(user, :admin_merge_request_approval_settings, project)
+                            .and_return(true)
+      end
+
+      it 'matches the response schema and updates the params' do
+        put api(url, user), params: params
+
+        expect(project.reset_approvals_on_push).to be true
+
+        expect(response).to match_response_schema('public_api/v4/group_merge_request_approval_settings', dir: 'ee')
+      end
+    end
+  end
 end

ee/spec/services/merge_request_approval_settings/update_service_spec.rb

@@ -3,20 +3,58 @@
 require 'spec_helper'
 
 RSpec.describe MergeRequestApprovalSettings::UpdateService do
-  let_it_be_with_reload(:group) { create(:group) }
+  let!(:group) { create(:group) }
+  let!(:project) { create(:project, merge_requests_author_approval: true) }
   let_it_be(:user) { create(:user) }
 
-  let(:params) { { allow_author_approval: true } }
+  let(:params) { { allow_author_approval: false } }
 
   subject(:service) do
     described_class.new(
-      container: group,
+      container: container,
       current_user: user,
       params: params
     )
   end
 
-  describe 'execute' do
+  describe 'execute with a Project as container' do
+    let(:container) { project }
+
+    context 'user does not have permissions' do
+      before do
+        allow(service).to receive(:can?).with(user, :admin_merge_request_approval_settings, container).and_return(false)
+      end
+
+      it 'responds with an error response', :aggregate_failures do
+        response = subject.execute
+
+        expect(response.status).to eq(:error)
+        expect(response.message).to eq('Insufficient permissions')
+      end
+
+      it 'does not change any of the approval settings' do
+        expect { subject.execute }.not_to change { project.attributes }
+      end
+    end
+
+    context 'user has permissions' do
+      before do
+        allow(service).to receive(:can?).with(user, :admin_merge_request_approval_settings, container).and_return(true)
+      end
+
+      it 'responds with a successful service response', :aggregate_failures do
+        response = subject.execute
+
+        expect(response).to be_success
+        expect(response.payload.reload.merge_requests_author_approval).to be(false)
+        expect(project.reload.merge_requests_author_approval).to be(false)
+      end
+    end
+  end
+
+  describe 'execute with a Group as container' do
+    let(:container) { group }
+
     context 'user does not have permissions' do
       before do
         allow(service).to receive(:can?).with(user, :admin_merge_request_approval_settings, group).and_return(false)
@@ -45,7 +83,7 @@ RSpec.describe MergeRequestApprovalSettings::UpdateService do
         response = subject.execute
 
         expect(response).to be_success
-        expect(response.payload.allow_author_approval).to be(true)
+        expect(response.payload.allow_author_approval).to be(false)
       end
 
       context 'when group has an existing setting' do
@@ -53,16 +91,14 @@ RSpec.describe MergeRequestApprovalSettings::UpdateService do
         let_it_be(:existing_setting) { create(:group_merge_request_approval_setting, group: group) }
 
         it 'does not create a new setting' do
-          expect { subject.execute }
-            .to change { GroupMergeRequestApprovalSetting.count }.by(0)
-            .and change { existing_setting.reload.allow_author_approval }.to(true)
+          expect { subject.execute }.not_to change { GroupMergeRequestApprovalSetting.count }
         end
 
         it 'responds with a successful service response', :aggregate_failures do
           response = subject.execute
 
           expect(response).to be_success
-          expect(response.payload.allow_author_approval).to be(true)
+          expect(response.payload.allow_author_approval).to be(false)
         end
       end