Change test runner on --fail-fast to report first error deterministic…

…ally

lib/mutant/reporter/cli/printer/test.rb

@@ -68,7 +68,7 @@ class EnvResult < self
  #
  # @return [undefined]
  def run
- visit_collection(Result, object.failed_test_results)
+ visit_failed
  visit(Env, object.env)
  FORMATS.each do |report, format, value|
  __send__(report, format, __send__(value))
@@ -77,6 +77,32 @@ def run
 
  private
 
+ def visit_failed
+ failed = object.failed_test_results
+
+ if object.env.config.fail_fast
+ visit_failed_tests(failed.take(1))
+ visit_other_failed(failed.drop(1))
+ else
+ visit_failed_tests(failed)
+ end
+ end
+
+ def visit_other_failed(other)
+ return if other.empty?
+
+ puts(
+ colorize(
+ Unparser::Color::RED,
+ 'Other failed tests (report suppressed from fail fast): %d' % other.length
+ )
+ )
+ end
+
+ def visit_failed_tests(failed)
+ visit_collection(Result, failed)
+ end
+
  def efficiency_percent
  (testtime / runtime) * 100
  end