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Testing Faraday Middleware Integration in VCR

This test suite validates the VCR middleware integration with Faraday HTTP client library, ensuring proper middleware insertion and request handling. The tests verify middleware positioning, adapter handling, and data callback functionality.

Test Coverage Overview

The test suite provides comprehensive coverage of VCR’s Faraday middleware functionality.

Key areas tested include:

Middleware insertion before HTTP adapters
Handling of missing adapters
Duplicate middleware prevention
on_data callback functionality

Integration points focus on Faraday builder configuration and HTTP request processing.

Implementation Analysis

The testing approach utilizes RSpec to verify middleware behavior in various Faraday configurations. Tests employ builder pattern verification and response handling checks.

Key patterns include:

Connection builder manipulation
Middleware stack inspection
Response streaming verification
Cassette playback validation

Technical Details

Testing tools and configuration:

RSpec for test framework
VCR for HTTP interaction recording
Faraday HTTP client library
Sinatra test server for live requests
Custom middleware implementation
Net::HTTP adapter testing

Best Practices Demonstrated

The test suite exemplifies strong testing practices through isolated test cases and comprehensive scenario coverage.

Notable practices include:

Context-based test organization
Edge case handling
Middleware stack validation
Callback testing patterns
Before/after state verification

vcr/vcr

spec/lib/vcr/library_hooks/faraday_spec.rb

            
require 'spec_helper'
require 'vcr/library_hooks/faraday'

RSpec.describe "Faraday hook" do
  it 'inserts the VCR middleware just before the adapter' do
    conn = Faraday.new(:url => 'http://sushi.com') do |builder|
      builder.request  :url_encoded
      builder.response :logger
      builder.adapter  :net_http
    end

    conn.builder.lock!
    expect(conn.builder.handlers.last.klass).to eq(VCR::Middleware::Faraday)
  end

  it 'handles the case where no adapter is declared' do
    conn = Faraday.new

    conn.builder.lock!
    expect(conn.builder.handlers.last.klass).to eq(VCR::Middleware::Faraday)
  end

  it 'does nothing if the VCR middleware has already been included' do
    conn = Faraday.new(:url => 'http://sushi.com') do |builder|
      builder.use VCR::Middleware::Faraday
    end

    conn.builder.lock!
    expect(conn.builder.handlers).to eq([VCR::Middleware::Faraday])
  end

  it 'gracefully handles the case where there is no explicit HTTP adapter' do
    conn = Faraday.new(:url => 'http://sushi.com') do |builder|
      builder.request  :url_encoded
      builder.response :logger
    end

    conn.builder.lock!
    expect(conn.builder.handlers.map(&:klass)).to eq([
      Faraday::Request::UrlEncoded,
      Faraday::Response::Logger,
      VCR::Middleware::Faraday
    ])
  end

  context 'when using on_data callback' do
    def make_request(&on_data_callback)
      VCR.use_cassette('no_body') do
        conn = Faraday.new(:url => "http://localhost:#{VCR::SinatraApp.port}") do |builder|
          builder.request  :url_encoded
          builder.adapter  :net_http
        end
        conn.get("localhost_test") do |request|
          request.options.on_data = on_data_callback
        end
      end
    end

    it { expect { |b| make_request(&b) }.to yield_with_args('Localhost response', 18) }
    it { expect(make_request {|_,_|}.body).to eq 'Localhost response' }

    context 'after recording' do
      before { make_request {|_, _|} }

      it { expect { |b| make_request(&b) }.to yield_with_args('Localhost response', 18) }
      it { expect(make_request {|_,_|}.body).to eq 'Localhost response' }
    end
  end
end