```ruby
require 'spec_helper'

describe JsonValidator do
  before do
    run_migration do
      create_table(:users, force: true) do |t|
        t.string :name
        t.json :profile
      end
    end

    spawn_model :User do
      schema = {
        "type" => "object",
        "$schema" => "http://json-schema.org/draft-03/schema",
        "properties" => {
          "city" => { "type" => "string", "required" => false },
          "country" => { "type" => "string", "required" => true }
        }
      }

      validates :name, presence: true
      validates :profile, presence: true, json: { schema: schema }
    end
  end

  context 'with blank JSON value' do
    let(:attributes) { { name: 'Samuel Garneau', profile: {} } }
    it { expect(User.new(attributes)).to_not be_valid }
  end

  context 'with invalid JSON value' do
    let(:attributes) { { name: 'Samuel Garneau', profile: { city: 'Quebec City' } } }
    it { expect(User.new(attributes)).to_not be_valid }
  end

  context 'with valid JSON value' do
    let(:attributes) { { name: 'Samuel Garneau', profile: { country: 'CA' } } }
    it { expect(User.new(attributes)).to be_valid }
  end
end
```

Use symbols instead of string for schema in specs
user
```ruby
require 'spec_helper'

describe JsonValidator do
  before do
    run_migration do
      create_table(:users, force: true) do |t|
        t.string :name
        t.json :profile
      end
    end

    spawn_model :User do
      schema = {
        type: 'object',
        :'$schema' => 'http://json-schema.org/draft-03/schema',
        properties: {
          city: { type: 'string', required: false },
          country: { type: 'string', required: true }
        }
      }

      validates :name, presence: true
      validates :profile, presence: true, json: { schema: schema }
    end
  end

  context 'with blank JSON value' do
    let(:attributes) { { name: 'Samuel Garneau', profile: {} } }
    it { expect(User.new(attributes)).to_not be_valid }
  end

  context 'with invalid JSON value' do
    let(:attributes) { { name: 'Samuel Garneau', profile: { city: 'Quebec City' } } }
    it { expect(User.new(attributes)).to_not be_valid }
  end

  context 'with valid JSON value' do
    let(:attributes) { { name: 'Samuel Garneau', profile: { country: 'CA' } } }
    it { expect(User.new(attributes)).to be_valid }
  end
end
```
assistant