You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: type_map_cache_spec.rb
    path of file: ./repos/gitlabhq/spec/lib/gitlab/database/postgresql_adapter
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

require 'spec_helper'

RSpec.describe Gitlab::Database::PostgresqlAdapter::TypeMapCache do
  let(:db_config) { ActiveRecord::Base.configurations.find_db_config(Rails.env).configuration_hash }
  let(:adapter_class) { ActiveRecord::ConnectionAdapters::PostgreSQLAdapter }

  before do
    adapter_class.type_map_cache.clear
  end

  describe '#initialize_type_map' do
    it 'caches loa
    
  def initialize_connection(config = db_config)
    conn_params = config.symbolize_keys.compact

    conn_params[:user] = conn_params.delete(:username) if conn_params[:username]
    conn_params[:dbname] = conn_params.delete(:database) if conn_params[:database]

    valid_conn_param_keys = PG::Connection.conndefaults_hash.keys + [:requiressl]
    conn_params.slice!(*valid_conn_param_keys)

    adapter_class.new(
      adapter_class.new_client(conn_params),
      ActiveRecord::Base.logger,
      conn_params,
      config
    )
  end