[CI] Log test results to a file in Buildkite

Author: picandocodigo

.buildkite/pipeline.yml

@@ -33,7 +33,9 @@ steps:
       TRANSPORT_VERSION: "{{ matrix.transport }}"
       RUBY_SOURCE: "{{ matrix.ruby_source }}"
       TEST_SUITE: "platinum"
+      DEBUG: true
     command: ./.buildkite/run-yaml-tests.sh
+    artifact_paths: "elasticsearch-api/tmp/*"
   - wait: ~
     continue_on_failure: true
   - label: "Log Results"

elasticsearch-api/spec/yaml-test-runner/run.rb

@@ -56,9 +56,9 @@
          end
 
 tests_path = File.expand_path('./tmp', __dir__)
-
-logger = Logger.new($stdout)
-logger.level = Logger::WARN unless ENV['DEBUG']
+logfile = File.expand_path "../../tmp/tests-#{Elasticsearch::VERSION}-transport-#{ENV['TRANSPORT_VERSION']}-ruby-#{ENV['RUBY_VERSION']}.log", __dir__
+logger = Logger.new(File.open(logfile, 'w'))
+logger.level = ENV['DEBUG'] ? Logger::DEBUG : Logger::WARN
 
 # If we're running in a release branch, download the corresponding branch for tests
 current_branch = `git rev-parse --abbrev-ref HEAD`.strip