post.yml

one:
  name: MyString
  email: MyString

two:
  name: MyString
  email: MyString

valid:
  name: ysn
  email: ysn@kobiks.com

old:
  name: Old
  email: old@example.com
  created_at: <%= 2.weeks.ago %>

user model

#app/models/user.rb

class User < ApplicationRecord
  scope :recent, -> { where('created_at > ?', 1.week.ago) }
  has_many :posts
  validates :name, :email, presence: true
end

user test

#test/models/user_test.rb

require 'test_helper'

class UserTest < ActiveSupport::TestCase

  def setup
    @user = users(:valid)
  end

  test 'valid user' do
    assert @user.valid?
  end

  test 'invalid without name' do
    @user.name = nil
    refute @user.valid?
    assert_not_nil @user.errors[:name]
  end

  test 'invalid without email' do
    @user.email = nil
    refute @user.valid?
    assert_not_nil @user.errors[:email]
  end

  test '#posts' do
    assert_equal 2, @user.posts.size
  end

  test '#recent' do
    assert_includes User.recent, users(:valid)
    refute_includes User.recent, users(:old)
  end
end

user.yml

one:
  name: MyString
  email: MyString

two:
  name: MyString
  email: MyString

valid:
  name: ysn
  email: ysn@kobiks.com

old:
  name: Old
  email: old@example.com
  created_at: <%= 2.weeks.ago %>