Set Rspec default GET request format to JSON

Question

I am doing functional tests for my controllers with Rspec. I have set my default response format in my router to JSON, so every request without a suffix will return JSON.

Answer 1

Here is a solution that

1. works for request specs,
2. works with Rails 5, and
3. does not involve private API of Rails (like process).

Here's the RSpec configuration:

module DefaultFormat
  extend ActiveSupport::Concern

  included do
    let(:default_format) { 'application/json' }
    prepend RequestHelpersCustomized
  end

  module RequestHelpersCustomized
    l = lambda do |path, **kwarg|
      kwarg[:headers] = {accept: default_format}.merge(kwarg[:headers] || {})
      super(path, **kwarg)
    end
    %w(get post patch put delete).each do |method|
      define_method(method, l)
    end
  end
end

RSpec.configure do |config|
  config.include DefaultFormat, type: :request
end

Verified with

describe 'the response format', type: :request do
  it 'can be overridden in request' do
    get some_path, headers: {accept: 'text/plain'}
    expect(response.content_type).to eq('text/plain')
  end

  context 'with default format set as HTML' do
    let(:default_format) { 'text/html' }

    it 'is HTML in the context' do
      get some_path
      expect(response.content_type).to eq('text/html')
    end
  end
end

FWIW, The RSpec configuration can be placed:

1. Directly in spec/spec_helper.rb. This is not suggested; the file will be loaded even when testing library methods in lib/.

2. Directly in spec/rails_helper.rb.

3. (my favorite) In spec/support/default_format.rb, and be loaded explicitly in spec/rails_helper.rb with

   require 'support/default_format'
   

4. In spec/support, and be loaded by

   Dir[Rails.root.join('spec/support/**/*.rb')].each { |f| require f }
   

   which loads all the files in spec/support.

This solution is inspired by knoopx's answer. His solution doesn't work for request specs, and alias_method_chain has been deprecated in favor of Module#prepend.