Suggest bisect_runner = :shell when there was a problem.

Author: myronmarston

lib/rspec/core/formatters/bisect_progress_formatter.rb

@@ -6,6 +6,11 @@ module Formatters
       # @private
       # Produces progress output while bisecting.
       class BisectProgressFormatter < BaseTextFormatter
+        def initialize(output, bisect_runner)
+          super(output)
+          @bisect_runner = bisect_runner
+        end
+
         def bisect_starting(notification)
           @round_count = 0
           output.puts bisect_started_message(notification)
@@ -30,6 +35,16 @@ def bisect_dependency_check_passed(_notification)
 
         def bisect_dependency_check_failed(_notification)
           output.puts " failure(s) do not require any non-failures to run first"
+
+          if @bisect_runner == :fork
+            output.puts
+            output.puts "=" * 80
+            output.puts "NOTE: this bisect run used `config.bisect_runner = :fork`, which generally"
+            output.puts "provides significantly faster bisection runs than the old shell-based runner,"
+            output.puts "but may inaccurately report that no non-failures are required. If this result"
+            output.puts "is unexpected, consider setting `config.bisect_runner = :shell` and trying again."
+            output.puts "=" * 80
+          end
         end
 
         def bisect_round_started(notification, include_trailing_space=true)

lib/rspec/core/invocations.rb

@@ -28,26 +28,23 @@ def call(options, err, out)
       class Bisect
         def call(options, err, out)
           RSpec::Support.require_rspec_core "bisect/coordinator"
+          runner = Runner.new(options).tap { |r| r.configure(err, out) }
+          formatter = bisect_formatter_klass_for(options.options[:bisect]).new(
+            out, runner.configuration.bisect_runner
+          )
 
           success = RSpec::Core::Bisect::Coordinator.bisect_with(
-            Runner.new(options).tap { |r| r.configure(err, out) },
-            options.args,
-            bisect_formatter_for(options.options[:bisect], out)
+            runner, options.args, formatter
           )
 
           success ? 0 : 1
         end
 
       private
 
-        def bisect_formatter_for(argument, output)
-          klass = if argument == "verbose"
-                    Formatters::BisectDebugFormatter
-                  else
-                    Formatters::BisectProgressFormatter
-                  end
-
-          klass.new(output)
+        def bisect_formatter_klass_for(argument)
+          return Formatters::BisectDebugFormatter if argument == "verbose"
+          Formatters::BisectProgressFormatter
         end
       end
 

spec/rspec/core/bisect/coordinator_spec.rb

@@ -16,8 +16,8 @@ module RSpec::Core
       )
     end
 
-    def find_minimal_repro(output, formatter=Formatters::BisectProgressFormatter)
-      Bisect::Coordinator.bisect_with(spec_runner, [], formatter.new(output))
+    def find_minimal_repro(output, formatter=Formatters::BisectProgressFormatter, bisect_runner = :fork)
+      Bisect::Coordinator.bisect_with(spec_runner, [], formatter.new(output, bisect_runner))
     end
 
     it 'notifies the bisect progress formatter of progress and closes the output' do
@@ -99,7 +99,7 @@ def find_minimal_repro(output, formatter=Formatters::BisectProgressFormatter)
       it "detects the independent case and prints the minimal reproduction" do
         fake_bisect_runner.dependent_failures = {}
         output = StringIO.new
-        find_minimal_repro(output)
+        find_minimal_repro(output, Formatters::BisectProgressFormatter, :shell)
         output = normalize_durations(output.string)
 
         expect(output).to eq(<<-EOS.gsub(/^\s+\|/, ''))
@@ -116,6 +116,33 @@ def find_minimal_repro(output, formatter=Formatters::BisectProgressFormatter)
         EOS
       end
 
+      it "also indicates that the :fork runner may be at fault when that was used" do
+        fake_bisect_runner.dependent_failures = {}
+        output = StringIO.new
+        find_minimal_repro(output, Formatters::BisectProgressFormatter, :fork)
+        output = normalize_durations(output.string)
+
+        expect(output).to eq(<<-EOS.gsub(/^\s+\|/, ''))
+          |Bisect started using options: ""
+          |Running suite to find failures... (n.nnnn seconds)
+          |Starting bisect with 1 failing example and 7 non-failing examples.
+          |Checking that failure(s) are order-dependent... failure(s) do not require any non-failures to run first
+          |
+          |================================================================================
+          |NOTE: this bisect run used `config.bisect_runner = :fork`, which generally
+          |provides significantly faster bisection runs than the old shell-based runner,
+          |but may inaccurately report that no non-failures are required. If this result
+          |is unexpected, consider setting `config.bisect_runner = :shell` and trying again.
+          |================================================================================
+          |
+          |Bisect complete! Reduced necessary non-failing examples from 7 to 0 in n.nnnn seconds.
+          |
+          |The minimal reproduction command is:
+          |  rspec 2.rb[1:1]
+
+        EOS
+      end
+
       it "can use the debug formatter for detailed output" do
         fake_bisect_runner.dependent_failures = {}
         output = StringIO.new