tools/src/execwrapper/execwrapper.go

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// Package oswrapper provides interfaces for the exec package.
// This facilitates better testing via dependency injection.
package execwrapper

import (
	"context"
	"errors"
	"io"
)

var (
	ErrCombinedOutputWithWriters = errors.New("RunWithCombinedOutput cannot be called with custom writers")
)

// ExecWrapper is a factory for dependency injection wrappers for calls to exec
type ExecWrapper interface {
	// Command is a builder for CmdWrappers without a provided Context
	Command(name string, args ...string) CmdWrapper
	// CommandContext is a builder for CmdWrappers with a provided Context
	CommandContext(ctx context.Context, name string, args ...string) CmdWrapper
}

// CmdWrapper is a dependency injection wrapper around calls to exec
type CmdWrapper interface {
	// WithStdout returns a new CmdWrapper with the output stream set.
	WithStdout(stdout io.Writer) CmdWrapper
	// WithStderr returns a new CmdWrapper with the error stream set.
	WithStderr(stderr io.Writer) CmdWrapper
	// Run executes the Cmd.
	Run() error
	// RunWithCombinedOutput executes the Cmd and returns its combined output. Calling this with stdout or stderr set return ErrCombinedOutputWithWriters.
	RunWithCombinedOutput() ([]byte, error)
}