Git Bisect: Only the Current Branch

git-bisect-branch.sh

#!/usr/bin/env bash
while getopts 'b:dh' OPTION; do
  case "$OPTION" in
    b)
      divergent_branch=$OPTARG
      ;;
    d)
      debug=true
      ;;
    h)
      echo "This is a script that performs a git-bisect over all commits from the current branch's HEAD to where the branch diverged from the supplied branch."
      echo ""
      echo "script usage: git-bisect-branch [-b branch] [-d] [-h] run_command" >&2
      echo ""
      echo "example: git-bisect-branch -d -b main ruby test.rb"
      echo ""
      echo "Arguments:"
      echo " - Use '-b' to specify the branch from which your current branch has diverged, this should typically be 'main'/'master'."
      echo " - Use '-d' to debug internal variables and see the verbose output of git commands."
      echo " - Use '-h' to see this message."
      echo " - The remainder of the command is interpreted as the run_command, that will be running at each bisect step."
      echo ""
      echo "If this script is on your PATH, you will be able to use it like 'git bisect-branch'."
      echo ""
      exit 1
      ;;
  esac
done
shift "$(($OPTIND -1))"

run_command=$*
current_branch=$(git branch --show-current)
current_branch_sha=$(git rev-parse HEAD)

if [ -z "$divergent_branch" ]
  then
  echo "No branch argument supplied. Should be the 'main/master' branch name"
  exit
fi

if [ -z "$run_command" ]
  then
  echo "No run_command argument supplied. Should be the command you will use to run tests for each bisect step"
  exit
fi

branching_sha=$(git merge-base $divergent_branch $current_branch)

echo "Starting bisect of commits on '$current_branch' branch ($current_branch_sha) since branching from '$divergent_branch' branch ($branching_sha)"

print_hline () {
  printf '%.s─' $(seq 1 $(tput cols))
}

if [ -n "$debug" ]
  then

  print_hline
  echo "run_command: $run_command"
  echo "current_branch: $current_branch"
  echo "current_branch_sha: $current_branch_sha"
  echo "divergent_branch: $divergent_branch"
  echo "branching_sha: $branching_sha"
  print_hline

  git bisect start
  git bisect good $branching_sha
  git bisect bad $current_branch_sha

  git bisect run $run_command
  echo ""
  print_hline
else
  git bisect start > /dev/null
  git bisect good $branching_sha > /dev/null
  git bisect bad $current_branch_sha > /dev/null
  git bisect run $run_command > /dev/null
fi

echo "Don't forget to 'git bisect reset'"