Class: Synthra::MockServer

Inherits:
Object
  • Object
show all
Defined in:
lib/synthra/mock_server.rb

Overview

Production-Ready Mock Server with Recording

A full-featured mock server that can:

  • Serve generated data via REST API
  • Record real API responses for replay
  • Support multiple response modes
  • Handle rate limiting and behaviors

Examples:

Start server

Synthra::MockServer.start(schema_dir: "schemas/", port: 3000)

With recording

server = Synthra::MockServer.new(schema_dir: "schemas/", recording: true)
server.start

Constant Summary collapse

DEFAULT_PORT = 
3000

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(schema_dir:, **options) ⇒ MockServer

Create a new mock server

Parameters:

  • schema_dir (String) —

    directory containing DSL schemas

  • options (Hash) —

    server options

Options Hash (**options):

  • :port (Integer) —

    Server port (default: 3000)

  • :recording (Boolean) —

    Enable request recording

  • :recordings_dir (String) —

    Directory for recordings

  • :cors (Boolean) —

    Enable CORS headers

  • :rate_limit (Integer) —

    Requests per minute (0 = unlimited)

  • :default_mode (Symbol) —

    Default generation mode



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# File 'lib/synthra/mock_server.rb', line 40

def initialize(schema_dir:, **options)
  @options = {
    port: DEFAULT_PORT,
    recording: false,
    recordings_dir: "recordings",
    cors: true,
    rate_limit: 0,
    default_mode: :random
  }.merge(options)

  @registry = Registry.new
  @registry.load_dir(schema_dir)
  @recordings = {}
  @request_counts = Hash.new(0)
  @last_reset = Time.now
  # Monitor (reentrant) so handle_recording can call save_recordings without self-deadlock.
  @mutex = Monitor.new

  load_recordings if @options[:recording]
end

Instance Attribute Details

#options ⇒ Object (readonly)

Returns the value of attribute options.



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# File 'lib/synthra/mock_server.rb', line 25

def options
  @options
end

#recordings ⇒ Object (readonly)

Returns the value of attribute recordings.



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# File 'lib/synthra/mock_server.rb', line 25

def recordings
  @recordings
end

#registry ⇒ Object (readonly)

Returns the value of attribute registry.



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# File 'lib/synthra/mock_server.rb', line 25

def registry
  @registry
end

Class Method Details

.start(**options) ⇒ Object 



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# File 'lib/synthra/mock_server.rb', line 111

def start(**options)
  new(**options).start
end

Instance Method Details

#add_cors_headers(res) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 398

def add_cors_headers(res)
  res["Access-Control-Allow-Origin"] = "*"
  res["Access-Control-Allow-Methods"] = "GET, POST, OPTIONS"
  res["Access-Control-Allow-Headers"] = "Content-Type, Authorization"
  res["Access-Control-Max-Age"] = "86400"
end

#apply_behaviors(schema, res) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 381

def apply_behaviors(schema, res)
  schema.behaviors.each do |behavior|
    case behavior[:type]
    when :latency
      min_ms = behavior[:min_ms] || 0
      max_ms = behavior[:max_ms] || min_ms
      delay = rand(min_ms..max_ms) / 1000.0
      sleep(delay)
    when :failure
      if rand < (behavior[:rate] || 0)
        res.status = behavior[:status] || 500
        throw :response_sent
      end
    end
  end
end
 


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# File 'lib/synthra/mock_server.rb', line 118

def banner
  <<~BANNER
    ╔═══════════════════════════════════════════════════════════════╗
    ║                                                               ║
    ║   🎲 Synthra Mock Server                                  ║
    ║                                                               ║
    ║   Production-ready data generation API                        ║
    ║   http://localhost:#{@options[:port].to_s.ljust(5)}                                     ║
    ║                                                               ║
    ╚═══════════════════════════════════════════════════════════════╝
  BANNER
end

#handle_batch_generate(req, res, schema_name) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 252

def handle_batch_generate(req, res, schema_name)
  schema_name = normalize_schema_name(schema_name)
  
  unless @registry.schema?(schema_name)
    res.status = 404
    res["Content-Type"] = "application/json"
    res.body = JSON.generate({ error: "Schema not found" })
    return
  end

  schema = @registry.schema(schema_name)
  params = parse_query_params(req)
  count = [params[:count] || 10, 10000].min

  data = schema.generate_many(
    count,
    seed: params[:seed],
    mode: params[:mode] || @options[:default_mode],
    registry: @registry
  )

  apply_behaviors(schema, res)

  res["Content-Type"] = "application/json"
  res.body = JSON.pretty_generate({
    data: data,
    meta: {
      count: data.length,
      seed: params[:seed],
      mode: (params[:mode] || @options[:default_mode]).to_s,
      schema: schema_name
    }
  })
end

#handle_generate(req, res, schema_name) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 190

def handle_generate(req, res, schema_name)
  schema_name = normalize_schema_name(schema_name)
  
  unless @registry.schema?(schema_name)
    res.status = 404
    res["Content-Type"] = "application/json"
    res.body = JSON.generate({
      error: "Schema not found",
      schema: schema_name,
      available: @registry.names
    })
    return
  end

  schema = @registry.schema(schema_name)
  params = parse_query_params(req)
  
  data = schema.generate(
    seed: params[:seed],
    mode: params[:mode] || @options[:default_mode],
    registry: @registry
  )

  # Apply behaviors (latency, failure)
  apply_behaviors(schema, res)

  res["Content-Type"] = "application/json"
  res.body = JSON.pretty_generate(data)

  record_response(schema_name, data) if @options[:recording]
end

#handle_generate_with_overrides(req, res, schema_name) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 222

def handle_generate_with_overrides(req, res, schema_name)
  schema_name = normalize_schema_name(schema_name)
  
  unless @registry.schema?(schema_name)
    res.status = 404
    res["Content-Type"] = "application/json"
    res.body = JSON.generate({ error: "Schema not found" })
    return
  end

  schema = @registry.schema(schema_name)
  body = JSON.parse(req.body || "{}") rescue {}
  
  overrides = body["overrides"] || {}
  count = body["count"] || 1
  seed = body["seed"]
  mode = (body["mode"] || @options[:default_mode]).to_sym

  if count > 1
    data = schema.generate_many(count, seed: seed, mode: mode, registry: @registry, overrides: overrides)
  else
    data = schema.generate(seed: seed, mode: mode, registry: @registry, overrides: overrides)
  end

  apply_behaviors(schema, res)

  res["Content-Type"] = "application/json"
  res.body = JSON.pretty_generate(data)
end

#handle_list_schemas(_req, res) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 181

def handle_list_schemas(_req, res)
  res["Content-Type"] = "application/json"
  res.body = JSON.pretty_generate({
    schemas: @registry.names.sort,
    count: @registry.names.count,
    endpoints: @registry.names.map { |n| "/api/#{to_snake_case(n)}" }
  })
end

#handle_recording(req, res, name) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 341

def handle_recording(req, res, name)
  @mutex.synchronize do
    if req.request_method == "POST"
      # Save recording
      body = JSON.parse(req.body || "{}") rescue {}
      @recordings[name] = {
        data: body["data"],
        recorded_at: Time.now.iso8601,
        content_type: body["content_type"] || "application/json"
      }
      save_recordings

      res["Content-Type"] = "application/json"
      res.body = JSON.generate({ saved: name })
    elsif @recordings[name]
      recording = @recordings[name]
      res["Content-Type"] = recording["content_type"] || "application/json"
      res.body = recording["data"].is_a?(String) ? recording["data"] : JSON.generate(recording["data"])
    else
      res.status = 404
      res["Content-Type"] = "application/json"
      res.body = JSON.generate({ error: "Recording not found", name: name })
    end
  end
end

#handle_schema_info(_req, res, schema_name) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 312

def handle_schema_info(_req, res, schema_name)
  schema_name = normalize_schema_name(schema_name)
  
  unless @registry.schema?(schema_name)
    res.status = 404
    res["Content-Type"] = "application/json"
    res.body = JSON.generate({ error: "Schema not found" })
    return
  end

  schema = @registry.schema(schema_name)
  
  res["Content-Type"] = "application/json"
  res.body = JSON.pretty_generate({
    name: schema.name,
    fields: schema.fields.map do |f|
      {
        name: f.name,
        type: f.type_name,
        optional: f.optional?,
        nullable: f.nullable?,
        args: f.type_args
      }
    end,
    behaviors: schema.behaviors,
    version: schema.respond_to?(:version) ? schema.version : nil
  })
end

#handle_stream_generate(req, res, schema_name) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 287

def handle_stream_generate(req, res, schema_name)
  schema_name = normalize_schema_name(schema_name)
  
  unless @registry.schema?(schema_name)
    res.status = 404
    res["Content-Type"] = "application/json"
    res.body = JSON.generate({ error: "Schema not found" })
    return
  end

  schema = @registry.schema(schema_name)
  params = parse_query_params(req)
  count = [params[:count] || 100, 100000].min

  res["Content-Type"] = "application/x-ndjson"
  res["Transfer-Encoding"] = "chunked"

  # Stream NDJSON
  output = +""
  schema.generate_stream(count: count, mode: params[:mode] || @options[:default_mode]).each do |record|
    output << JSON.generate(record) << "\n"
  end
  res.body = output
end

#load_recordings ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 429

def load_recordings
  dir = @options[:recordings_dir]
  return unless Dir.exist?(dir)

  @mutex.synchronize do
    Dir.glob(File.join(dir, "*.json")).each do |file|
      name = File.basename(file, ".json")
      @recordings[name] = JSON.parse(File.read(file))
    end
  end
end

#normalize_schema_name(name) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 376

def normalize_schema_name(name)
  # Convert snake_case to PascalCase
  name.split("_").map(&:capitalize).join
end

#parse_query_params(req) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 367

def parse_query_params(req)
  query = req.query || {}
  {
    seed: query["seed"]&.to_i,
    mode: query["mode"]&.to_sym,
    count: query["count"]&.to_i
  }
end

#rate_limited?(req) ⇒ Boolean (private)

Returns:

  • (Boolean) 


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# File 'lib/synthra/mock_server.rb', line 405

def rate_limited?(req)
  client_ip = req.peeraddr[2]
  @mutex.synchronize do
    # Reset counts every minute
    if Time.now - @last_reset > 60
      @request_counts.clear
      @last_reset = Time.now
    end

    @request_counts[client_ip] += 1
    @request_counts[client_ip] > @options[:rate_limit]
  end
end

#record_response(schema_name, data) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 419

def record_response(schema_name, data)
  @mutex.synchronize do
    @recordings["#{schema_name}_#{Time.now.to_i}"] = {
      data: data,
      recorded_at: Time.now.iso8601,
      schema: schema_name
    }
  end
end

#route_request(req, res) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 153

def route_request(req, res)
  path = req.path
  method = req.request_method

  case path
  when "/api/schemas"
    handle_list_schemas(req, res)
  when %r{^/api/recordings/(.+)$}
    handle_recording(req, res, $1)
  when %r{^/api/([^/]+)/batch$}
    handle_batch_generate(req, res, $1)
  when %r{^/api/([^/]+)/stream$}
    handle_stream_generate(req, res, $1)
  when %r{^/api/([^/]+)/schema$}
    handle_schema_info(req, res, $1)
  when %r{^/api/([^/]+)$}
    if method == "POST"
      handle_generate_with_overrides(req, res, $1)
    else
      handle_generate(req, res, $1)
    end
  else
    res.status = 404
    res["Content-Type"] = "application/json"
    res.body = JSON.generate({ error: "Not found", path: path })
  end
end

#save_recordings ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 441

def save_recordings
  dir = @options[:recordings_dir]
  FileUtils.mkdir_p(dir)

  @mutex.synchronize do
    @recordings.each do |name, data|
      File.write(File.join(dir, "#{name}.json"), JSON.pretty_generate(data))
    end
  end
end

#setup_routes ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 131

def setup_routes
  # CORS preflight
  @server.mount_proc "/" do |req, res|
    add_cors_headers(res) if @options[:cors]
    
    if req.request_method == "OPTIONS"
      res.status = 204
      next
    end

    # Rate limiting
    if @options[:rate_limit] > 0 && rate_limited?(req)
      res.status = 429
      res["Content-Type"] = "application/json"
      res.body = JSON.generate({ error: "Rate limit exceeded" })
      next
    end

    route_request(req, res)
  end
end

#start ⇒ Object

Start the mock server



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# File 'lib/synthra/mock_server.rb', line 62

def start
  # :nocov: binds a real TCP port and blocks on WEBrick#start — exercised via integration use.
  puts banner
  puts ""
  puts "📊 Available schemas: #{@registry.names.sort.join(', ')}"
  puts ""
  puts "🔗 Endpoints:"
  puts "   GET  /api/schemas              - List all schemas"
  puts "   GET  /api/:schema              - Generate single record"
  puts "   GET  /api/:schema/batch        - Generate multiple records"
  puts "   GET  /api/:schema/stream       - Stream records (NDJSON)"
  puts "   POST /api/:schema              - Generate with overrides"
  puts "   GET  /api/:schema/schema       - Get schema definition"
  puts ""
  if @options[:recording]
    puts "📼 Recording mode: ENABLED"
    puts "   POST /api/recordings/:name     - Save recording"
    puts "   GET  /api/recordings/:name     - Replay recording"
    puts ""
  end
  puts "Press Ctrl+C to stop"
  puts ""

  @server = WEBrick::HTTPServer.new(
    Port: @options[:port],
    Logger: WEBrick::Log.new($stderr, WEBrick::Log::INFO),
    AccessLog: [[File.open("/dev/null", "w"), WEBrick::AccessLog::COMBINED_LOG_FORMAT]]
  )

  setup_routes

  trap("INT") { @server.shutdown }
  @server.start
  # :nocov:
end

#start_async ⇒ Object

Start server in background thread



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# File 'lib/synthra/mock_server.rb', line 99

def start_async
  # :nocov: spawns a thread that binds a port — integration-only.
  Thread.new { start }
  # :nocov:
end

#stop ⇒ Object

Stop the server



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# File 'lib/synthra/mock_server.rb', line 106

def stop
  @server&.shutdown
end

#to_snake_case(str) ⇒ Object (private) 



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# File 'lib/synthra/mock_server.rb', line 452

def to_snake_case(str)
  str.gsub(/([A-Z]+)([A-Z][a-z])/, '\1_\2')
     .gsub(/([a-z\d])([A-Z])/, '\1_\2')
     .downcase
end