[DOCS] Updates example docs generator to eval the code

This update adds a test module which instantiates an Elasticsearch
client and runs `eval` on the generated example code. It catches
exceptions for both Elasticsearch responses and client responses,
logging them to different files:

- logs/docs-generation-elasticsearch.log
- logs/docs-generation-client.log

This way we can generate the code, run it and check if there are
errors in the documentation, the client or the code generation.

It generates all the available examples and mutes all outputs in the
console, replacing it with a progress status.

Author: picandocodigo

rake_tasks/doc_generator.rake

@@ -17,6 +17,7 @@
 
 require 'json'
 require 'fileutils'
+require 'logger'
 
 namespace :docs do
   SRC_FILE          = "#{__dir__}/docs/parsed_alternative_report.json".freeze
@@ -29,13 +30,11 @@ namespace :docs do
     FileUtils.remove_dir(TARGET_DIR)
     Dir.mkdir(TARGET_DIR)
 
-    # Only select the files in the EXAMPLES_TO_PARSE array and that are not
-    # console result examples
-    entries = json_data.select do |d|
-      EXAMPLES_TO_PARSE.include? d['source_location']['file']
-    end.select { |d| d['lang'] == 'console' }
-
-    entries.each do |entry|
+    entries = json_data.select { |d| d['lang'] == 'console' }
+    entries.each_with_index do |entry, index|
+      percentage = index * 100 / entries.length
+      print "\r" + ("\e[A\e[K") if index > 0
+      puts "Generating file #{index + 1} of #{entries.length} - #{percentage}% complete"
       generate_docs(entry)
     end
   end
@@ -45,11 +44,12 @@ namespace :docs do
   end
 
   def generate_docs(entry)
-    file_name = "#{entry['digest']}.asciidoc"
+    filename = "#{entry['digest']}.asciidoc"
     unless entry['parsed_source'].empty?
       api = entry['parsed_source'].first['api']
       code = build_client_query(api, entry)
-      write_file(code, file_name)
+      TestDocs::perform(code, filename)
+      write_file(code, filename)
     end
   end
 
@@ -63,7 +63,8 @@ namespace :docs do
       request_body << show_parameters(params) if params
       body = entry&.[]('body')
       request_body << show_body(body) if body
-      request_body = request_body.compact.join(",\n")
+      request_body = request_body.compact.join(",\n").gsub('null', 'nil')
+
       code = "response = client.#{api}(\n#{request_body}\n)\nputs response"
       client_query << format_code(code)
     end
@@ -76,7 +77,7 @@ namespace :docs do
       f.puts code
     end
     # Format code:
-    system("rubocop --config #{__dir__}/docs_rubocop_config.yml --format autogenconf -a ./temp.rb")
+    system("rubocop --config #{__dir__}/docs_rubocop_config.yml -o /dev/null -a ./temp.rb")
     # Read it back
     template = File.read('./temp.rb')
     File.delete('./temp.rb')
@@ -122,3 +123,28 @@ namespace :docs do
     end
   end
 end
+
+#
+# Test module to run the generated code
+#
+module TestDocs
+  require 'elasticsearch'
+  @formatter = -> (_, d, _, msg) { "#{d}: #{msg}" }
+
+  def self.perform(code, filename)
+    # Eval the example code, but remove printing out the response
+    eval(code.gsub('puts response', ''))
+  rescue Elastic::Transport::Transport::Error => e
+    logger = Logger.new('log/docs-generation-elasticsearch.log')
+    logger.formatter = @formatter
+    logger.info("Located in #{filename}: #{e.message}\n")
+  rescue ArgumentError => e
+    logger = Logger.new('log/docs-generation-client.log')
+    logger.formatter = @formatter
+    logger.info("Located in #{filename}: #{e.message}\n")
+  end
+
+  def self.client
+    @client ||= Elasticsearch::Client.new(trace: false, log: false)
+  end
+end