Create spec for jsonb column with specific matcher

This MR makes sure we keep control on new jsonb column
introduced by enforcing developers to use a schema.

doc/development/migration_style_guide.md

@@ -810,6 +810,14 @@ class BuildMetadata
 end
 ```
 
+When using a `JSONB` column, use the [JsonSchemaValidator](https://gitlab.com/gitlab-org/gitlab/-/blob/master/app/validators/json_schema_validator.rb) to keep control of the data being inserted over time.
+
+```ruby
+class BuildMetadata
+  validates: :config_options, json_schema: { filename: 'build_metadata_config_option' }
+end
+```
+
 ## Testing
 
 See the [Testing Rails migrations](testing_guide/testing_migrations_guide.md) style guide.

lib/gitlab/background_migration/fix_pages_access_level.rb

@@ -16,7 +16,7 @@ module Gitlab
       end
 
       # Namespace
-      class Namespace < ApplicationRecord
+      class Namespace < ActiveRecord::Base
         self.table_name = 'namespaces'
         self.inheritance_column = :_type_disabled
 

spec/db/schema_spec.rb

@@ -8,6 +8,7 @@ RSpec.describe 'Database schema' do
 
   let(:connection) { ActiveRecord::Base.connection }
   let(:tables) { connection.tables }
+  let(:columns_name_with_jsonb) { retrieve_columns_name_with_jsonb }
 
   # Use if you are certain that this column should not have a foreign key
   # EE: edit the ee/spec/db/schema_support.rb
@@ -169,8 +170,54 @@ RSpec.describe 'Database schema' do
     end
   end
 
+  # These pre-existing columns does not use a schema validation yet
+  IGNORED_JSONB_COLUMNS = {
+    "ApplicationSetting" => %w[repository_storages_weighted],
+    "AlertManagement::Alert" => %w[payload],
+    "Ci::BuildMetadata" => %w[config_options config_variables],
+    "Geo::Event" => %w[payload],
+    "GeoNodeStatus" => %w[status],
+    "Operations::FeatureFlagScope" => %w[strategies],
+    "Operations::FeatureFlags::Strategy" => %w[parameters],
+    "Packages::Composer::Metadatum" => %w[composer_json],
+    "Releases::Evidence" => %w[summary]
+  }.freeze
+
+  # We are skipping GEO models for now as it adds up complexity
+  describe 'for jsonb columns' do
+    it 'uses json schema validator' do
+      columns_name_with_jsonb.each do |hash|
+        next if models_by_table_name[hash["table_name"]].nil?
+
+        models_by_table_name[hash["table_name"]].each do |model|
+          jsonb_columns = [hash["column_name"]] - ignored_jsonb_columns(model.name)
+
+          expect(model).to validate_jsonb_schema(jsonb_columns)
+        end
+      end
+    end
+  end
+
   private
 
+  def retrieve_columns_name_with_jsonb
+    sql = <<~SQL
+        SELECT table_name, column_name, data_type
+          FROM information_schema.columns
+        WHERE table_catalog = '#{ApplicationRecord.connection_config[:database]}'
+          AND table_schema = 'public'
+          AND table_name NOT LIKE 'pg_%'
+          AND data_type = 'jsonb'
+      ORDER BY table_name, column_name, data_type
+    SQL
+
+    ApplicationRecord.connection.select_all(sql).to_a
+  end
+
+  def models_by_table_name
+    @models_by_table_name ||= ApplicationRecord.descendants.reject(&:abstract_class).group_by(&:table_name)
+  end
+
   def ignored_fk_columns(column)
     IGNORED_FK_COLUMNS.fetch(column, [])
   end
@@ -178,4 +225,8 @@ RSpec.describe 'Database schema' do
   def ignored_limit_enums(model)
     IGNORED_LIMIT_ENUMS.fetch(model, [])
   end
+
+  def ignored_jsonb_columns(model)
+    IGNORED_JSONB_COLUMNS.fetch(model, [])
+  end
 end

spec/support/matchers/jsonb_matchers.rb

+# frozen_string_literal: true
+
+RSpec::Matchers.define :validate_jsonb_schema do |jsonb_columns|
+  match do |actual|
+    next true if jsonb_columns.blank?
+
+    expect(actual.validators).to include(a_kind_of(JsonSchemaValidator))
+  end
+
+  failure_message do
+    <<~FAILURE_MESSAGE
+      Expected #{actual.name} to validate the schema of #{jsonb_columns.join(', ')}.
+
+      Use JsonSchemaValidator in your model when using a jsonb column.
+      See doc/development/migration_style_guide.html#storing-json-in-database for more information.
+
+      To fix this, please add `validates :#{jsonb_columns.first}, json_schema: { filename: "filename" }` in your model file, for example:
+
+      class #{actual.name}
+        validates :#{jsonb_columns.first}, json_schema: { filename: "filename" }
+      end
+    FAILURE_MESSAGE
+  end
+end