Use the --bisect flag value rather than ENV var for verbose mode.

features/command_line/bisect.feature

@@ -6,7 +6,7 @@ Feature: Bisect
 
   At any point during the bisect run, you can hit ctrl-c to abort and it will provide you with the most minimal reproduction command it has discovered so far.
 
-  To get more detailed output (particularly useful if you want to report a bug with bisect), you can set the `DEBUG_RSPEC_BISECT` environment variable.
+  To get more detailed output (particularly useful if you want to report a bug with bisect), use `--bisect=verbose`.
 
   Background:
     Given a file named "lib/calculator.rb" with:
@@ -88,8 +88,8 @@ Feature: Bisect
     When I run `rspec ./spec/calculator_10_spec.rb[1:1] ./spec/calculator_1_spec.rb[1:1] ./spec/calculator_3_spec.rb[1:1] --seed 1234`
     Then the output should contain "3 examples, 1 failure"
 
-  Scenario: Use DEBUG_RSPEC_BISECT=1 to enable verbose debug mode for more detail
-    When I run `rspec --seed 1234 --bisect` with `DEBUG_RSPEC_BISECT=1` set
+  Scenario: Use `--bisect=verbose` to enable verbose debug mode for more detail
+    When I run `rspec --seed 1234 --bisect=verbose`
     Then bisect should succeed with output like:
       """
       Bisect started using options: "--seed 1234"

features/step_definitions/additional_cli_steps.rb

@@ -177,11 +177,6 @@
   expect(actual.sub(/\n+\Z/, '')).to eq(expected)
 end
 
-When(/^I run `([^`]+)` with `([^=]+)=([^`]+)` set$/) do |cmd, env_key, env_value|
-  set_env(env_key, env_value)
-  step "I run `#{cmd}`"
-end
-
 When(/^I run `([^`]+)` and abort in the middle with ctrl\-c$/) do |cmd|
   set_env('RUBYOPT', ENV['RUBYOPT'] + " -r#{File.expand_path("../../support/send_sigint_during_bisect.rb", __FILE__)}")
   step "I run `#{cmd}`"

lib/rspec/core/bisect/coordinator.rb

@@ -15,17 +15,18 @@ module Bisect
       #   - Formatters::BisectProgressFormatter: provides progress updates
       #     to the user.
       class Coordinator
-        def self.bisect_with(original_cli_args, configuration)
-          new(original_cli_args, configuration).bisect
+        def self.bisect_with(original_cli_args, configuration, formatter)
+          new(original_cli_args, configuration, formatter).bisect
         end
 
-        def initialize(original_cli_args, configuration)
+        def initialize(original_cli_args, configuration, formatter)
           @original_cli_args = original_cli_args
           @configuration     = configuration
+          @formatter         = formatter
         end
 
         def bisect
-          @configuration.add_formatter bisect_formatter
+          @configuration.add_formatter @formatter
 
           reporter.close_after do
             repro = Server.run do |server|
@@ -52,10 +53,6 @@ def reporter
           @configuration.reporter
         end
 
-        def bisect_formatter
-          ENV['DEBUG_RSPEC_BISECT'] ? Formatters::BisectDebugFormatter : Formatters::BisectProgressFormatter
-        end
-
         def gracefully_abort_on_sigint(minimizer)
           trap('INT') do
             repro = minimizer.repro_command_for_currently_needed_ids

lib/rspec/core/bisect/runner.rb

@@ -12,7 +12,7 @@ class Runner
 
         def initialize(server, original_cli_args)
           @server            = server
-          @original_cli_args = original_cli_args - ["--bisect"]
+          @original_cli_args = original_cli_args.reject { |arg| arg.start_with?("--bisect") }
         end
 
         def run(locations)

lib/rspec/core/option_parser.rb

@@ -62,9 +62,9 @@ def parser(options)
           options[:order] = "rand:#{seed}"
         end
 
-        parser.on('--bisect', 'Repeatedly runs the suite in order to isolate the failures to the ',
-                  '  smallest reproducible case.') do
-          bisect_and_exit
+        parser.on('--bisect [verbose]', 'Repeatedly runs the suite in order to isolate the failures to the ',
+                  '  smallest reproducible case.') do |argument|
+          bisect_and_exit(argument)
         end
 
         parser.on('--[no-]fail-fast', 'Abort the run on first failure.') do |value|
@@ -268,12 +268,23 @@ def initialize_project_and_exit
       exit
     end
 
-    def bisect_and_exit
+    def bisect_and_exit(argument)
       RSpec::Support.require_rspec_core "bisect/coordinator"
-      success = Bisect::Coordinator.bisect_with(original_args, RSpec.configuration)
+
+      success = Bisect::Coordinator.bisect_with(
+        original_args,
+        RSpec.configuration,
+        bisect_formatter_for(argument)
+      )
+
       exit(success ? 0 : 1)
     end
 
+    def bisect_formatter_for(argument)
+      return Formatters::BisectDebugFormatter if argument == "verbose"
+      Formatters::BisectProgressFormatter
+    end
+
     def print_version_and_exit
       puts RSpec::Core::Version::STRING
       exit

spec/rspec/core/bisect/coordinator_spec.rb

@@ -14,12 +14,12 @@ module RSpec::Core
       )
     end
 
-    def find_minimal_repro(output)
+    def find_minimal_repro(output, formatter=Formatters::BisectProgressFormatter)
       allow(Bisect::Server).to receive(:run).and_yield(instance_double(Bisect::Server))
       allow(Bisect::Runner).to receive(:new).and_return(fake_runner)
 
       RSpec.configuration.output_stream = output
-      Bisect::Coordinator.bisect_with([], RSpec.configuration)
+      Bisect::Coordinator.bisect_with([], RSpec.configuration, formatter)
     ensure
       RSpec.reset # so that RSpec.configuration.output_stream isn't closed
     end
@@ -47,7 +47,7 @@ def find_minimal_repro(output)
 
     it 'can use the bisect debug formatter to get detailed progress' do
       output = StringIO.new
-      with_env_vars('DEBUG_RSPEC_BISECT' => '1') { find_minimal_repro(output) }
+      find_minimal_repro(output, Formatters::BisectDebugFormatter)
       output = normalize_durations(output.string)
 
       expect(output).to eq(<<-EOS.gsub(/^\s+\|/, ''))
@@ -95,8 +95,8 @@ def find_minimal_repro(output)
     end
 
     context "when the user aborst the bisect with ctrl-c" do
-      before do
-        formatter_subclass = Class.new(Formatters::BisectProgressFormatter) do
+      let(:aborting_formatter) do
+        Class.new(Formatters::BisectProgressFormatter) do
           Formatters.register self
 
           def bisect_round_finished(notification)
@@ -111,14 +111,12 @@ def bisect_round_finished(notification)
             sleep 5
           end
         end
-
-        stub_const(Formatters::BisectProgressFormatter.name, formatter_subclass)
       end
 
       it "prints the most minimal repro command it has found so far" do
         output = StringIO.new
         expect {
-          find_minimal_repro(output)
+          find_minimal_repro(output, aborting_formatter)
         }.to raise_error(an_object_having_attributes(
           :class  => SystemExit,
           :status => 1

spec/rspec/core/bisect/runner_spec.rb

@@ -70,10 +70,12 @@ def command_for(locations, options={})
         expect(cmd.scan("--drb-port").count).to eq(1)
       end
 
-      it 'ignores the `--bisect` option since that would infinitely recurse' do
-        original_cli_args << "--bisect"
-        cmd = command_for([])
-        expect(cmd).to exclude("--bisect")
+      %w[ --bisect --bisect=verbose --bisect=blah ].each do |value|
+        it "ignores a `#{value}` option since that would infinitely recurse" do
+          original_cli_args << value
+          cmd = command_for([])
+          expect(cmd).to exclude(value)
+        end
       end
 
       it 'uses the bisect formatter' do