"errors"
	"io"
	"strings"
	"testing"
)

// DefaultCmds returns a set of broadly useful script commands.
//
// This set includes all of the commands in script.DefaultCmds,
// as well as a "skip" command that halts the script and causes the
// testing.TB passed to Run to be skipped.
func DefaultCmds() map[string]script.Cmd {
	cmds := script.DefaultCmds()
	cmds["skip"] = Skip()
	return cmds
}

	"cmd/go/internal/work"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"strings"
	"sync"
	"time"
)

func scriptCommands(interrupt os.Signal, waitDelay time.Duration) map[string]script.Cmd {
	cmds := scripttest.DefaultCmds()

	// Customize the "exec" interrupt signal and grace period.
	var cancel func(cmd *exec.Cmd) error
	if interrupt != nil {
		cancel = func(cmd *exec.Cmd) error {
			return cmd.Process.Signal(interrupt)
		}
	}

func newScriptEngine() *script.Engine {
	conds := script.DefaultConds()

	interrupt := func(cmd *exec.Cmd) error { return cmd.Process.Signal(os.Interrupt) }
	gracePeriod := 30 * time.Second // arbitrary

	cmds := script.DefaultCmds()
	cmds["at"] = scriptAt()
	cmds["bzr"] = script.Program("bzr", interrupt, gracePeriod)
	cmds["fossil"] = script.Program("fossil", interrupt, gracePeriod)
	cmds["git"] = script.Program("git", interrupt, gracePeriod)

	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"time"
)

// DefaultCmds returns a set of broadly useful script commands.
//
// Run the 'help' command within a script engine to view a list of the available
// commands.
func DefaultCmds() map[string]Cmd {
	return map[string]Cmd{
		"cat":     Cat(),
		"cd":      Cd(),
		"chmod":   Chmod(),
		"cmp":     Cmp(),

	// section when starting a new section.
	Quiet bool
}

// NewEngine returns an Engine configured with a basic set of commands and conditions.
func NewEngine() *Engine {
	return &Engine{
		Cmds:  DefaultCmds(),
		Conds: DefaultConds(),
	}
}

// A Cmd is a command that is available to a script.
type Cmd interface {
	// Run begins running the command.
	//