lib/parallel_tests/cli.rb in parallel_tests-1.6.0 vs lib/parallel_tests/cli.rb in parallel_tests-1.6.1

@@ -33,13 +33,14 @@
     def run_tests_in_parallel(num_processes, options)
       test_results = nil
 
       report_time_taken do
         groups = @runner.tests_in_groups(options[:files], num_processes, options)
+        groups.reject! &:empty?
 
         test_results = if options[:only_group]
-          groups_to_run = options[:only_group].collect{|i| groups[i - 1]}
+          groups_to_run = options[:only_group].collect{|i| groups[i - 1]}.compact
           report_number_of_tests(groups_to_run)
           execute_in_parallel(groups_to_run, groups_to_run.size, options) do |group|
             run_tests(group, groups_to_run.index(group), 1, options)
           end
         else
@@ -90,11 +91,12 @@
     end
 
     def report_number_of_tests(groups)
       name = @runner.test_file_name
       num_processes = groups.size
-      num_tests = groups.map(&:size).inject(:+)
-      puts "#{num_processes} processes for #{num_tests} #{name}s, ~ #{num_tests / groups.size} #{name}s per process"
+      num_tests = groups.map(&:size).inject(0, :+)
+      tests_per_process = (num_processes == 0 ? 0 : num_tests / num_processes)
+      puts "#{num_processes} processes for #{num_tests} #{name}s, ~ #{tests_per_process} #{name}s per process"
     end
 
     #exit with correct status code so rake parallel:test && echo 123 works
     def any_test_failed?(test_results)
       test_results.any? { |result| result[:exit_status] != 0 }