Cap approvals_required at 100

Fix migration to honor this cap

ee/app/models/concerns/approval_rule_like.rb

@@ -4,6 +4,7 @@ module ApprovalRuleLike
   extend ActiveSupport::Concern
 
   DEFAULT_NAME = 'Default'
+  APPROVALS_REQUIRED_MAX = 100
 
   included do
     has_and_belongs_to_many :users
@@ -11,6 +12,7 @@ module ApprovalRuleLike
     has_many :group_users, -> { distinct }, through: :groups, source: :users
 
     validates :name, presence: true
+    validates :approvals_required, numericality: { less_than_or_equal_to: APPROVALS_REQUIRED_MAX }
   end
 
   # Users who are eligible to approve, including specified group members.

ee/lib/gitlab/background_migration/migrate_approver_to_approval_rules.rb

@@ -162,7 +162,7 @@ module Gitlab
 
         unless rule.persisted?
           rule.name ||= ApprovalRuleLike::DEFAULT_NAME
-          rule.approvals_required = target.approvals_required
+          rule.approvals_required = [target.approvals_required, ApprovalRuleLike::APPROVALS_REQUIRED_MAX].min
           rule.save!
         end
 

ee/spec/lib/gitlab/background_migration/migrate_approver_to_approval_rules_spec.rb

@@ -154,6 +154,18 @@ describe Gitlab::BackgroundMigration::MigrateApproverToApprovalRules do
         end
       end
 
+      context 'when approvals_before_merge is too big' do
+        it "caps at allowed maximum" do
+          target.target_project.update(approvals_before_merge: ::ApprovalRuleLike::APPROVALS_REQUIRED_MAX + 1)
+          target.update(approvals_before_merge: nil)
+          create_member_in(create(:user), :old_schema)
+
+          described_class.new.perform(target_type, target.id)
+
+          expect(target.approval_rules.regular.first.approvals_required).to eq(::ApprovalRuleLike::APPROVALS_REQUIRED_MAX)
+        end
+      end
+
       context 'when approver is no longer overwritten' do
         before do
           create_member_in(create(:user), :new_schema)

ee/spec/models/concerns/approval_rule_like_spec.rb

@@ -74,6 +74,25 @@ describe ApprovalRuleLike do
         end
       end
     end
+
+    describe 'validation' do
+      context 'when value is too big' do
+        it 'is invalid' do
+          subject.approvals_required = described_class::APPROVALS_REQUIRED_MAX + 1
+
+          expect(subject).to be_invalid
+          expect(subject.errors.key?(:approvals_required)).to eq(true)
+        end
+      end
+
+      context 'when value is within limit' do
+        it 'is valid' do
+          subject.approvals_required = described_class::APPROVALS_REQUIRED_MAX
+
+          expect(subject).to be_valid
+        end
+      end
+    end
   end
 
   context 'MergeRequest' do