Guides > Testing

Testing

Controller Serializer Usage

ActiveModelSerializers provides a assert_serializer method to be used on your controller tests to assert that a specific serializer was used.

class PostsControllerTest < ActionController::TestCase
  test "should render post serializer" do
    get :index
    assert_serializer "PostSerializer"
  end
end

See ActiveModelSerializers::Test::Serializer for more examples and documentation.

Serialization against a schema

Dependencies

To use the assert_response_schema you need to have the json_schema on your Gemfile. Please add it to your Gemfile and run $ bundle install.

Minitest test helpers

ActiveModelSerializers provides a assert_response_schema method to be used on your controller tests to assert the response against a JSON Schema. Let's take a look in an example.

class PostsController < ApplicationController
  def show
    @post = Post.find(params[:id])

    render json: @post
  end
end

To test the posts#show response of this controller we need to create a file named test/support/schemas/posts/show.json. The helper uses a naming convention to locate the file.

This file is a JSON Schema representation of our response.

{
  "properties": {
    "title" : { "type" : "string" },
    "content" : { "type" : "string" }
  }
}

With all in place we can go to our test and use the helper.

class PostsControllerTest < ActionController::TestCase
  test "should render right response" do
    get :index
    assert_response_schema
  end
end

Load a custom schema

If we need to use another schema, for example when we have a namespaced API that shows the same response, we can pass the path of the schema.

module V1
  class PostsController < ApplicationController
    def show
      @post = Post.find(params[:id])

      render json: @post
    end
  end
end

class V1::PostsControllerTest < ActionController::TestCase
  test "should render right response" do
    get :index
    assert_response_schema('posts/show.json')
  end
end

Change the schema path

By default all schemas are created at test/support/schemas. If we are using RSpec for example we can change this to spec/support/schemas defining the default schema path in an initializer.

ActiveModelSerializers.config.schema_path = 'spec/support/schemas'

Using with the Heroku’s JSON Schema-based tools

To use the test helper with the prmd and committee.

We need to change the schema path to the recommended by prmd:

ActiveModelSerializers.config.schema_path = 'docs/schema/schemata'

We also need to structure our schemata according to Heroku's conventions (e.g. including required metadata and links.

JSON Pointers

If we plan to use JSON Pointers we need to define the id attribute on the schema. Example:

// attributes.json

{
  "id": "file://attributes.json#",
  "properties": {
    "name" : { "type" : "string" },
    "description" : { "type" : "string" }
  }
}

// show.json

{
  "properties": {
    "name": {
      "$ref": "file://attributes.json#/properties/name"
    },
    "description": {
      "$ref": "file://attributes.json#/properties/description"
    }
  }
}