Introduce functionality to bisect branch chains (#76)

.github/workflows/main.yml

@@ -16,6 +16,8 @@ jobs:
         ruby:
           - 3.0.3
           - 3.1.0
+          - 3.2.2
+          - 3.3.2
 
     steps:
     - uses: actions/checkout@v2

.rubocop.yml

@@ -13,11 +13,13 @@ AllCops:
 Bundler/GemVersion: { EnforcedStyle: forbidden }
 
 Metrics/BlockLength: { Exclude: ["spec/**/*_spec.rb"] }
+RSpec/MessageExpectation: { EnforcedStyle: expect }
 Style/ClassAndModuleChildren: { EnforcedStyle: compact }
 
 Style/MethodCallWithArgsParentheses:
   AllowedMethods:
     - abort
+    - and
     - describe
     - not_to
     - raise
@@ -38,6 +40,8 @@ Layout/LineLength:
 
 Bundler/GemComment: { Enabled: false }
 Lint/ConstantResolution: { Enabled: false }
+RSpec/StubbedMock: { Enabled: false }
 Style/ConstantVisibility: { Enabled: false }
 Style/Copyright: { Enabled: false }
 Style/InlineComment: { Enabled: false }
+Style/MissingElse: { Enabled: false }

.rubocop_todo.yml

@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config --auto-gen-only-exclude --exclude-limit 400`
-# on 2023-09-18 23:50:42 UTC using RuboCop version 1.56.2.
+# on 2024-06-12 23:47:02 UTC using RuboCop version 1.64.1.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -14,6 +14,27 @@ Bundler/GemVersion:
   Exclude:
     - 'Gemfile'
 
+# Offense count: 2
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: Max, AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, AllowedPatterns.
+# URISchemes: http, https
+Layout/LineLength:
+  Exclude:
+    - 'lib/baes/actions/bisect.rb'
+
+# Offense count: 2
+# Configuration parameters: AllowedMethods, AllowedPatterns, CountRepeatedAttributes, Max.
+Metrics/AbcSize:
+  Exclude:
+    - 'lib/baes/actions/bisect.rb'
+
+# Offense count: 4
+# Configuration parameters: CountComments, Max, CountAsOne, AllowedMethods, AllowedPatterns.
+Metrics/MethodLength:
+  Exclude:
+    - 'lib/baes/actions/bisect.rb'
+    - 'lib/baes/actions/run.rb'
+
 # Offense count: 1
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: EnforcedStyle.
@@ -22,43 +43,38 @@ RSpec/BeNil:
   Exclude:
     - 'spec/baes_spec.rb'
 
-# Offense count: 11
+# Offense count: 16
 # Configuration parameters: Max, CountAsOne.
 RSpec/ExampleLength:
   Exclude:
+    - 'spec/baes/actions/bisect_spec.rb'
     - 'spec/baes/actions/build_tree_spec.rb'
     - 'spec/baes/actions/rebase_spec.rb'
     - 'spec/baes/branch_spec.rb'
 
 # Offense count: 1
-# Configuration parameters: Include, CustomTransform, IgnoreMethods, SpecSuffixOnly.
-# Include: **/*_spec*rb*, **/spec/**/*
-RSpec/FilePath:
-  Exclude:
-    - 'spec/baes/actions/load_configuration_spec.rb'
-
-# Offense count: 9
 # Configuration parameters: EnforcedStyle.
 # SupportedStyles: allow, expect
 RSpec/MessageExpectation:
   Exclude:
-    - 'spec/baes/git_spec.rb'
+    - 'spec/support/stub_system.rb'
 
-# Offense count: 9
+# Offense count: 11
 # Configuration parameters: .
 # SupportedStyles: have_received, receive
 RSpec/MessageSpies:
   EnforcedStyle: receive
 
-# Offense count: 6
+# Offense count: 5
 # Configuration parameters: Max.
 RSpec/MultipleExpectations:
   Exclude:
     - 'spec/baes/actions/build_tree_spec.rb'
-    - 'spec/baes/actions/load_configuration_spec.rb'
     - 'spec/baes/git_spec.rb'
 
-# Offense count: 9
-RSpec/StubbedMock:
+# Offense count: 1
+# Configuration parameters: AllowedPatterns.
+# AllowedPatterns: ^expect_, ^assert_
+RSpec/NoExpectationExample:
   Exclude:
-    - 'spec/baes/git_spec.rb'
+    - 'spec/baes/actions/bisect_spec.rb'

lib/baes/actions.rb

@@ -3,7 +3,9 @@
 # namespace for callable modules
 module Baes::Actions; end
 
+require_relative "actions/bisect"
 require_relative "actions/build_tree"
 require_relative "actions/load_configuration"
+require_relative "actions/load_rebase_configuration"
 require_relative "actions/rebase"
 require_relative "actions/run"

lib/baes/actions/bisect.rb

@@ -0,0 +1,91 @@
+# frozen_string_literal: true
+
+# class that will attempt to locate the first branch in the current chain that
+# fails with a given command
+module Baes::Actions::Bisect
+  class << self
+    include Baes::Configuration::Helpers
+
+    # run the command and return the first branch that fails
+    def call(command_args)
+      output.puts("searching for branch that fails command: `#{command_args}`")
+      branches = generate_branches
+      root_branch = find_root_branch(branches)
+      Baes::Actions::BuildTree.call(branches, root_branch: root_branch)
+
+      current_branch_name = git.current_branch_name
+      current_branch =
+        branches.find { |branch| branch.name == current_branch_name }
+
+      _, _, status = Open3.capture3(command_args)
+
+      if status.success?
+        raise ArgumentError, "command must fail to find failure"
+      end
+
+      fail_branch =
+        find_failing_branch(root_branch, current_branch, command_args)
+
+      git.checkout(fail_branch.name)
+      output.puts("first failing branch: #{fail_branch.name}")
+    end
+
+    private
+
+    def generate_branches
+      git.branch_names.map do |branch_name|
+        Baes::Branch.new(branch_name)
+      end
+    end
+
+    def find_root_branch(branches)
+      if root_name
+        branches.find { |branch| branch.name == root_name }
+      else
+        branches.find { |branch| ["main", "master"].include?(branch.name) }
+      end
+    end
+
+    def find_failing_branch(success_branch, fail_branch, command_args)
+      next_branch = find_middle_branch(success_branch, fail_branch)
+
+      return fail_branch if next_branch == fail_branch || next_branch.nil?
+
+      git.checkout(next_branch.name)
+      _, _, status = Open3.capture3(command_args)
+
+      if status.success?
+        output.puts("branch #{next_branch.name} succeeded with command `#{command_args}`")
+        find_failing_branch(next_branch, fail_branch, command_args)
+      else
+        output.puts("branch #{next_branch.name} failed with command `#{command_args}`")
+        find_failing_branch(success_branch, next_branch, command_args)
+      end
+    end
+
+    def find_middle_branch(success_branch, fail_branch)
+      end_number = fail_branch.number
+      start_number = success_branch.number
+
+      child_branch =
+        success_branch.children.find do |next_child_branch|
+          next_child_branch.base_name == fail_branch.base_name
+        end
+
+      start_number ||= child_branch.number
+
+      middle_number = (start_number + end_number) / 2
+
+      next_branch = child_branch
+
+      while next_branch.number < middle_number
+        next_branch =
+          next_branch.children.find do |next_child_branch|
+            next_child_branch.base_name == fail_branch.base_name
+          end
+      end
+
+      next_branch
+    end
+  end
+end

lib/baes/actions/load_configuration.rb

@@ -9,49 +9,18 @@ class << self
     def call(options)
       parser = OptionParser.new
 
-      configure_dry_run(parser)
       configure_help(parser)
-      configure_root_name(parser)
-      configure_auto_skip(parser)
-      configure_ignored_branches(parser)
 
       parser.parse(options)
     end
 
     private
 
-    def configure_dry_run(parser)
-      parser.on("--dry-run", "prints branch chain without rebasing") do
-        Baes::Configuration.dry_run = true
-      end
-    end
-
     def configure_help(parser)
       parser.on("-h", "--help", "prints this help") do
         Baes::Configuration.output.puts(parser)
         exit
       end
     end
-
-    def configure_root_name(parser)
-      message = "specify a root branch to rebase on"
-      parser.on("-r", "--root ROOT", message) do |root_name|
-        Baes::Configuration.root_name = root_name
-      end
-    end
-
-    def configure_auto_skip(parser)
-      message = "automatically skip all but the most recent commit"
-      parser.on("--auto-skip", message) do
-        Baes::Configuration.auto_skip = true
-      end
-    end
-
-    def configure_ignored_branches(parser)
-      message = "don't rebase specified branches or their child branches"
-      parser.on("--ignore BRANCH1,BRANCH2", Array, message) do |branches|
-        Baes::Configuration.ignored_branch_names += branches
-      end
-    end
   end
 end

lib/baes/actions/load_rebase_configuration.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+require "optparse"
+
+# callable module to load configuration
+module Baes::Actions::LoadRebaseConfiguration
+  class << self
+    # loads options, typically passed via the command line
+    def call(options)
+      parser = OptionParser.new
+
+      configure_dry_run(parser)
+      configure_help(parser)
+      configure_root_name(parser)
+      configure_auto_skip(parser)
+      configure_ignored_branches(parser)
+
+      parser.parse(options)
+    end
+
+    private
+
+    def configure_dry_run(parser)
+      parser.on("--dry-run", "prints branch chain without rebasing") do
+        Baes::Configuration.dry_run = true
+      end
+    end
+
+    def configure_help(parser)
+      parser.on("-h", "--help", "prints this help") do
+        Baes::Configuration.output.puts(parser)
+        exit
+      end
+    end
+
+    def configure_root_name(parser)
+      message = "specify a root branch to rebase on"
+      parser.on("-r", "--root ROOT", message) do |root_name|
+        Baes::Configuration.root_name = root_name
+      end
+    end
+
+    def configure_auto_skip(parser)
+      message = "automatically skip all but the most recent commit"
+      parser.on("--auto-skip", message) do
+        Baes::Configuration.auto_skip = true
+      end
+    end
+
+    def configure_ignored_branches(parser)
+      message = "don't rebase specified branches or their child branches"
+      parser.on("--ignore BRANCH1,BRANCH2", Array, message) do |branches|
+        Baes::Configuration.ignored_branch_names += branches
+      end
+    end
+  end
+end

lib/baes/actions/run.rb

@@ -4,8 +4,19 @@
 module Baes::Actions::Run
   # parse options and execute command
   def self.call(options)
-    Baes::Actions::LoadConfiguration.call(options)
+    case options.first
+    when "bisect"
+      Baes::Actions::Bisect.call(options[1..].join(" "))
+    when "rebase"
+      Baes::Actions::LoadRebaseConfiguration.call(options)
 
-    Baes::Actions::Rebase.call
+      Baes::Actions::Rebase.call
+    when nil
+      Baes::Actions::LoadConfiguration.call(["-h"])
+    when /^-/
+      Baes::Actions::LoadConfiguration.call(options)
+    else
+      abort("Invalid command #{options.inspect}")
+    end
   end
 end

lib/baes/git.rb

@@ -31,6 +31,17 @@ def self.rebase(branch_name)
     status
   end
 
+  # get current branch name and raise on error
+  def self.current_branch_name
+    stdout, stderr, status = Open3.capture3("git rev-parse --abbrev-ref HEAD")
+
+    output.puts(stderr) unless stderr.empty?
+
+    raise GitError, "failed to get current branch" unless status.success?
+
+    stdout.strip
+  end
+
   # list branch names and raise on failure
   def self.branch_names
     stdout, stderr, status = Open3.capture3("git branch")