expect

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 Go to latest Published: Sep 2, 2021 License: BSD-3-Clause Imports: 15 Imported by: 1

README

CircleCI

This package is an implementation of Expect in Go.

Features:

  • Spawning and controlling local processes with real PTYs.
  • Native SSH spawner.
  • Expect backed spawner for testing.
  • Generic spawner to make implementing additional Spawners simple.
  • Has a batcher for implementing workflows without having to write extra logic and code.

Options

All Spawn functions accept a variadic of type expect.Option , these are used for changing options of the Expecter.

CheckDuration

The Go Expecter checks for new data every two seconds as default. This can be changed by using the CheckDuration func CheckDuration(d time.Duration) Option.

Verbose

The Verbose option is used to turn on/off verbose logging for Expect/Send statements. This option can be very useful when troubleshooting workflows since it will log every interaction with the device.

VerboseWriter

The VerboseWriter option can be used to change where the verbose session logs are written. Using this option will start writing verbose output to the provided io.Writer instead of the log default.

See the ExampleVerbose code for an example of how to use this.

NoCheck

The Go Expecter periodically checks that the spawned process/ssh/session/telnet etc. session is alive. This option turns that check off.

DebugCheck

The DebugCheck option adds debugging to the alive Check done by the Expecter, this will start logging information every time the check is run. Can be used for troubleshooting and debugging of Spawners.

ChangeCheck

The ChangeCheck option makes it possible to replace the Spawner Check function with a brand new one.

SendTimeout

The SendTimeout set timeout on the Send command, without timeout the Send command will wait forewer for the expecter process.

BufferSize

The BufferSize option provides a mechanism to configure the client io buffer size in bytes.

Basic Examples

networkbit.ch

An article with some examples was written about goexpect on networkbit.ch.

The Wikipedia Expect examples.

Telnet

First we try to replicate the Telnet example from wikipedia as close as possible.

Interaction:

+ username:
- user\n
+ password:
- pass\n
+ %
- cmd\n
+ %
- exit\n

Error checking was omitted to keep the example short

package main

import (
	"flag"
	"fmt"
	"log"
	"regexp"
	"time"

	"github.com/google/goexpect"
	"github.com/google/goterm/term"
)

const (
	timeout = 10 * time.Minute
)

var (
	addr = flag.String("address", "", "address of telnet server")
	user = flag.String("user", "", "username to use")
	pass = flag.String("pass", "", "password to use")
	cmd  = flag.String("cmd", "", "command to run")

	userRE   = regexp.MustCompile("username:")
	passRE   = regexp.MustCompile("password:")
	promptRE = regexp.MustCompile("%")
)

func main() {
	flag.Parse()
	fmt.Println(term.Bluef("Telnet 1 example"))

	e, _, err := expect.Spawn(fmt.Sprintf("telnet %s", *addr), -1)
	if err != nil {
		log.Fatal(err)
	}
	defer e.Close()

	e.Expect(userRE, timeout)
	e.Send(*user + "\n")
	e.Expect(passRE, timeout)
	e.Send(*pass + "\n")
	e.Expect(promptRE, timeout)
	e.Send(*cmd + "\n")
	result, _, _ := e.Expect(promptRE, timeout)
	e.Send("exit\n")

	fmt.Println(term.Greenf("%s: result: %s\n", *cmd, result))
}

In essence to run and attach to a process the expect.Spawn(<cmd>,<timeout>) is used. The spawn returns an Expecter e that can run e.Expect and e.Send commands to match information in the output and Send information in.

See the https://github.com/google/goexpect/blob/master/examples/newspawner/telnet.go example for a slightly more fleshed out version

FTP

For the FTP example we use the expect.Batch for the following interaction.

+ username:
- user\n
+ password:
- pass\n
+ ftp>
- prompt\n
+ ftp>
- mget *\n
+ ftp>'
- bye\n

ftp_example.go

package main

import (
	"flag"
	"fmt"
	"log"
	"time"

	"github.com/google/goexpect"
	"github.com/google/goterm/term"
)

const (
	timeout = 10 * time.Minute
)

var (
	addr = flag.String("address", "", "address of telnet server")
	user = flag.String("user", "", "username to use")
	pass = flag.String("pass", "", "password to use")
)

func main() {
	flag.Parse()
	fmt.Println(term.Bluef("Ftp 1 example"))

	e, _, err := expect.Spawn(fmt.Sprintf("ftp %s", *addr), -1)
	if err != nil {
		log.Fatal(err)
	}
	defer e.Close()

	e.ExpectBatch([]expect.Batcher{
		&expect.BExp{R: "username:"},
		&expect.BSnd{S: *user + "\n"},
		&expect.BExp{R: "password:"},
		&expect.BSnd{S: *pass + "\n"},
		&expect.BExp{R: "ftp>"},
		&expect.BSnd{S: "bin\n"},
		&expect.BExp{R: "ftp>"},
		&expect.BSnd{S: "prompt\n"},
		&expect.BExp{R: "ftp>"},
		&expect.BSnd{S: "mget *\n"},
		&expect.BExp{R: "ftp>"},
		&expect.BSnd{S: "bye\n"},
	}, timeout)

	fmt.Println(term.Greenf("All done"))
}

Using the expect.Batcher makes the standard Send/Expect interactions more compact and simpler to write.

SSH

With the SSH login example we test out the expect.Caser and the Case Tags.

Also for this we'll use the Go Expect native SSH Spawner instead of spawning a process.

Interaction:

+ "Login: "
- user
+ "Password: "
- pass1
+ "Wrong password"
+ "Login"
- user
+ "Password: "
- pass2
+ router#

ssh_example.go

package main

import (
	"flag"
	"fmt"
	"log"
	"regexp"
	"time"

	"golang.org/x/crypto/ssh"

	"google.golang.org/grpc/codes"

	"github.com/google/goexpect"
	"github.com/google/goterm/term"
)

const (
	timeout = 10 * time.Minute
)

var (
	addr  = flag.String("address", "", "address of telnet server")
	user  = flag.String("user", "user", "username to use")
	pass1 = flag.String("pass1", "pass1", "password to use")
	pass2 = flag.String("pass2", "pass2", "alternate password to use")
)

func main() {
	flag.Parse()
	fmt.Println(term.Bluef("SSH Example"))

	sshClt, err := ssh.Dial("tcp", *addr, &ssh.ClientConfig{
		User:            *user,
		Auth:            []ssh.AuthMethod{ssh.Password(*pass1)},
		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
	})
	if err != nil {
		log.Fatalf("ssh.Dial(%q) failed: %v", *addr, err)
	}
	defer sshClt.Close()

	e, _, err := expect.SpawnSSH(sshClt, timeout)
	if err != nil {
		log.Fatal(err)
	}
	defer e.Close()

	e.ExpectBatch([]expect.Batcher{
		&expect.BCas{[]expect.Caser{
			&expect.Case{R: regexp.MustCompile(`router#`), T: expect.OK()},
			&expect.Case{R: regexp.MustCompile(`Login: `), S: *user,
				T: expect.Continue(expect.NewStatus(codes.PermissionDenied, "wrong username")), Rt: 3},
			&expect.Case{R: regexp.MustCompile(`Password: `), S: *pass1, T: expect.Next(), Rt: 1},
			&expect.Case{R: regexp.MustCompile(`Password: `), S: *pass2,
				T: expect.Continue(expect.NewStatus(codes.PermissionDenied, "wrong password")), Rt: 1},
		}},
	}, timeout)

	fmt.Println(term.Greenf("All done"))
}

Generic Spawner

The Go Expect package supports adding new Spawners with the func SpawnGeneric(opt *GenOptions, timeout time.Duration, opts ...Option) (*GExpect, <-chan error, error) function.

telnet spawner

From the newspawner example.

func telnetSpawn(addr string, timeout time.Duration, opts ...expect.Option) (expect.Expecter, <-chan error, error) {
	conn, err := telnet.Dial(network, addr)
	if err != nil {
		return nil, nil, err
	}

	resCh := make(chan error)

	return expect.SpawnGeneric(&expect.GenOptions{
		In:  conn,
		Out: conn,
		Wait: func() error {
			return <-resCh
		},
		Close: func() error {
			close(resCh)
			return conn.Close()
		},
		Check: func() bool { return true },
	}, timeout, opts...)
}

Fake Spawner

The Go Expect package includes a Fake Spawner func SpawnFake(b []Batcher, timeout time.Duration, opt ...Option) (*GExpect, <-chan error, error). This is expected to be used to simplify testing and faking of interactive workflows.

Fake Spawner

// TestExpect tests the Expect function.
func TestExpect(t *testing.T) {
	tests := []struct {
		name    string
		fail    bool
		srv     []Batcher
		timeout time.Duration
		re      *regexp.Regexp
	}{{
		name: "Match prompt",
		srv: []Batcher{
			&BSnd{`
Pretty please don't hack my chassis

router1> `},
		},
		re:      regexp.MustCompile("router1>"),
		timeout: 2 * time.Second,
	}, {
		name: "Match fail",
		fail: true,
		re:   regexp.MustCompile("router1>"),
		srv: []Batcher{
			&BSnd{`
Welcome

Router42>`},
		},
		timeout: 1 * time.Second,
	}}

	for _, tst := range tests {
		exp, _, err := SpawnFake(tst.srv, tst.timeout)
		if err != nil {
			if !tst.fail {
				t.Errorf("%s: SpawnFake failed: %v", tst.name, err)
			}
			continue
		}
		out, _, err := exp.Expect(tst.re, tst.timeout)
		if got, want := err != nil, tst.fail; got != want {
			t.Errorf("%s: Expect(%q,%v) = %t want: %t , err: %v, out: %q", tst.name, tst.re.String(), tst.timeout, got, want, err, out)
			continue
		}
	}
}

Disclaimer: This is not an official Google product.

Documentation

Overview

Package expect is a Go version of the classic TCL Expect.

Index

Examples

Constants

View Source 
const (
	// BatchSend for invoking Send in a batch
	BatchSend = iota
	// BatchExpect for invoking Expect in a batch
	BatchExpect
	// BatchSwitchCase for invoking ExpectSwitchCase in a batch
	BatchSwitchCase
	// BatchSendSignal for invoking SendSignal in a batch.
	BatchSendSignal
)

BatchCommands.

View Source 
const (
	// OKTag marks the desired state was reached.
	OKTag = Tag(iota)
	// FailTag means reaching this state will fail the Switch/Case.
	FailTag
	// ContinueTag will recheck for matches.
	ContinueTag
	// NextTag skips match and continues to the next one.
	NextTag
	// NoTag signals no tag was set for this case.
	NoTag
)
View Source 
const DefaultTimeout = 60 * time.Second

DefaultTimeout is the default Expect timeout.

Variables

This section is empty.

Functions

func Continue 

func Continue(s *Status) func() (Tag, *Status)

Continue returns the Continue Tag and status.

func Fail 

func Fail(s *Status) func() (Tag, *Status)

Fail returns Fail Tag and status.

func LogContinue 

func LogContinue(msg string, s *Status) func() (Tag, *Status)

LogContinue logs the message and returns the Continue Tag and status.

func Next 

func Next() func() (Tag, *Status)

Next returns the Next Tag and status.

func OK 

func OK() func() (Tag, *Status)

OK returns the OK Tag and status.

Types

type BCas 

type BCas struct {
	// C holds the Caser array for the SwitchCase command.
	C []Caser
}

BCas implements the Batcher interface for SwitchCase commands.

func (*BCas) Arg 

func (bc *BCas) Arg() string

Arg returns an empty string , not used for SwitchCase.

func (*BCas) Cases 

func (bc *BCas) Cases() []Caser

Cases returns the Caser structure.

func (*BCas) Cmd 

func (bc *BCas) Cmd() int

Cmd returns the SwitchCase command(BatchSwitchCase).

func (*BCas) Timeout 

func (bc *BCas) Timeout() time.Duration

Timeout returns -1 , setting it to the default value.

type BCasT 

type BCasT struct {
	// Cs holds the Caser array for the SwitchCase command.
	C []Caser
	// Tout holds the SwitchCase timeout in seconds.
	T int
}

BCasT implements the Batcher interfacs for SwitchCase commands, adding a timeout option to the BCas type.

func (*BCasT) Arg 

func (bct *BCasT) Arg() string

Arg returns an empty string , not used for SwitchCase.

func (*BCasT) Cases 

func (bct *BCasT) Cases() []Caser

Cases returns the Caser structure.

func (*BCasT) Cmd 

func (bct *BCasT) Cmd() int

Cmd returns the SwitchCase command(BatchSwitchCase).

func (*BCasT) Timeout 

func (bct *BCasT) Timeout() time.Duration

Timeout returns the timeout in seconds.

type BCase 

type BCase struct {
	// R contains the string regular expression.
	R string
	// S contains the string to be sent if R matches.
	S string
	// T contains the Tag.
	T func() (Tag, *Status)
	// Rt contains the number of retries.
	Rt int
}

BCase with just a string is a bit more friendly to scripting. Implements the Caser interface.

func (*BCase) RE 

func (b *BCase) RE() (*regexp.Regexp, error)

RE returns the compiled regular expression.

func (*BCase) Retry 

func (b *BCase) Retry() bool

Retry decrements the Retry counter and checks if there are any retries left.

func (*BCase) String 

func (b *BCase) String() string

Send returns the string to send.

func (*BCase) Tag 

func (b *BCase) Tag() (Tag, *Status)

Tag returns the BCase Tag.

type BExp 

type BExp struct {
	// R contains the Expect command regular expression.
	R string
}

BExp implements the Batcher interface for Expect commands using the default timeout.

func (*BExp) Arg 

func (be *BExp) Arg() string

Arg returns the Expect regular expression.

func (*BExp) Cases 

func (be *BExp) Cases() []Caser

Cases always returns nil for the Expect command.

func (*BExp) Cmd 

func (be *BExp) Cmd() int

Cmd returns the Expect command (BatchExpect).

func (*BExp) Timeout 

func (be *BExp) Timeout() time.Duration

Timeout always returns -1 which sets it to the value used to call the ExpectBatch function.

type BExpT 

type BExpT struct {
	// R contains the Expect command regular expression.
	R string
	// T holds the Expect command timeout in seconds.
	T int
}

BExpT implements the Batcher interface for Expect commands adding a timeout option to the BExp type.

func (*BExpT) Arg 

func (bt *BExpT) Arg() string

Arg returns the Expect regular expression.

func (*BExpT) Cases 

func (bt *BExpT) Cases() []Caser

Cases always return nil for the Expect command.

func (*BExpT) Cmd 

func (bt *BExpT) Cmd() int

Cmd returns the Expect command (BatchExpect).

func (*BExpT) Timeout 

func (bt *BExpT) Timeout() time.Duration

Timeout returns the timeout in seconds.

type BSig 

type BSig struct {
	// S contains the signal.
	S syscall.Signal
}

BSig implements the Batcher interface for SendSignal commands.

func (*BSig) Arg 

func (bs *BSig) Arg() string

Arg returns the signal integer.

func (*BSig) Cases 

func (bs *BSig) Cases() []Caser

Cases always returns nil for BSig.

func (*BSig) Cmd 

func (bs *BSig) Cmd() int

Cmd returns the SendSignal command (BatchSendSignal).

func (*BSig) Timeout 

func (bs *BSig) Timeout() time.Duration

Timeout always returns 0 for BSig.

type BSnd 

type BSnd struct {
	S string
}

BSnd implements the Batcher interface for Send commands.

func (*BSnd) Arg 

func (bs *BSnd) Arg() string

Arg returns the data to be sent.

func (*BSnd) Cases 

func (bs *BSnd) Cases() []Caser

Cases always returns nil , not used for Send commands.

func (*BSnd) Cmd 

func (bs *BSnd) Cmd() int

Cmd returns the Send command(BatchSend).

func (*BSnd) Timeout 

func (bs *BSnd) Timeout() time.Duration

Timeout always returns 0 , Send doesn't have a timeout.

type BatchRes 

type BatchRes struct {
	// Idx is used to match the result with the []Batcher commands sent in.
	Idx int
	// Out output buffer for the expect command at Batcher[Idx].
	Output string
	// Match regexp matches for expect command at Batcher[Idx].
	Match []string
}

BatchRes returned from ExpectBatch for every Expect command executed.

type Batcher 

type Batcher interface {
	// cmd returns the Batch command.
	Cmd() int
	// Arg returns the command argument.
	Arg() string
	// Timeout returns the timeout duration for the command , <0 gives default value.
	Timeout() time.Duration
	// Cases returns the Caser structure for SwitchCase commands.
	Cases() []Caser
}

Batcher interface is used to make it more straightforward and readable to create batches of Expects. 

var batch = []Batcher{
	&BExpT{"password",8},
	&BSnd{"password\n"},
	&BExp{"olakar@router>"},
	&BSnd{ "show interface description\n"},
	&BExp{ "olakar@router>"},
}

var batchSwCaseReplace = []Batcher{
	&BCasT{[]Caser{
		&BCase{`([0-9]) -- .*\(MASTER\)`, `\1` + "\n"}}, 1},
	&BExp{`prompt/>`},
}

type Case 

type Case struct {
	// R is the compiled regexp to match.
	R *regexp.Regexp
	// S is the string to send if Regexp matches.
	S string
	// T is the Tag for this Case.
	T func() (Tag, *Status)
	// Rt specifies number of times to retry, only used for cases tagged with Continue.
	Rt int
}

Case used by the ExpectSwitchCase to take different Cases. Implements the Caser interface.

func (*Case) RE 

func (c *Case) RE() (*regexp.Regexp, error)

RE returns the compiled regular expression.

func (*Case) Retry 

func (c *Case) Retry() bool

Retry decrements the Retry counter and checks if there are any retries left.

func (*Case) String 

func (c *Case) String() string

Send returns the string to send if regexp matches

func (*Case) Tag 

func (c *Case) Tag() (Tag, *Status)

Tag returns the tag for this case.

type Caser 

type Caser interface {
	// RE returns a compiled regexp
	RE() (*regexp.Regexp, error)
	// Send returns the send string
	String() string
	// Tag returns the Tag.
	Tag() (Tag, *Status)
	// Retry returns true if there are retries left.
	Retry() bool
}

Caser is an interface for ExpectSwitchCase and Batch to be able to handle both the Case struct and the more script friendly BCase struct.

type Code 

type Code uint32

A Code is an unsigned 32-bit error code as defined in the gRPC spec. 

const (
	// OK is returned on success.
	StatusOK Code = 0

	// Canceled indicates the operation was canceled (typically by the caller).
	//
	// The gRPC framework will generate this error code when cancellation
	// is requested.
	Canceled Code = 1

	// Unknown error. An example of where this error may be returned is
	// if a Status value received from another address space belongs to
	// an error-space that is not known in this address space. Also
	// errors raised by APIs that do not return enough error information
	// may be converted to this error.
	//
	// The gRPC framework will generate this error code in the above two
	// mentioned cases.
	Unknown Code = 2

	// InvalidArgument indicates client specified an invalid argument.
	// Note that this differs from FailedPrecondition. It indicates arguments
	// that are problematic regardless of the state of the system
	// (e.g., a malformed file name).
	//
	// This error code will not be generated by the gRPC framework.
	InvalidArgument Code = 3

	// DeadlineExceeded means operation expired before completion.
	// For operations that change the state of the system, this error may be
	// returned even if the operation has completed successfully. For
	// example, a successful response from a server could have been delayed
	// long enough for the deadline to expire.
	//
	// The gRPC framework will generate this error code when the deadline is
	// exceeded.
	DeadlineExceeded Code = 4

	// NotFound means some requested entity (e.g., file or directory) was
	// not found.
	//
	// This error code will not be generated by the gRPC framework.
	NotFound Code = 5

	// AlreadyExists means an attempt to create an entity failed because one
	// already exists.
	//
	// This error code will not be generated by the gRPC framework.
	AlreadyExists Code = 6

	// PermissionDenied indicates the caller does not have permission to
	// execute the specified operation. It must not be used for rejections
	// caused by exhausting some resource (use ResourceExhausted
	// instead for those errors). It must not be
	// used if the caller cannot be identified (use Unauthenticated
	// instead for those errors).
	//
	// This error code will not be generated by the gRPC core framework,
	// but expect authentication middleware to use it.
	PermissionDenied Code = 7

	// ResourceExhausted indicates some resource has been exhausted, perhaps
	// a per-user quota, or perhaps the entire file system is out of space.
	//
	// This error code will be generated by the gRPC framework in
	// out-of-memory and server overload situations, or when a message is
	// larger than the configured maximum size.
	ResourceExhausted Code = 8

	// FailedPrecondition indicates operation was rejected because the
	// system is not in a state required for the operation's execution.
	// For example, directory to be deleted may be non-empty, an rmdir
	// operation is applied to a non-directory, etc.
	//
	// A litmus test that may help a service implementor in deciding
	// between FailedPrecondition, Aborted, and Unavailable:
	//  (a) Use Unavailable if the client can retry just the failing call.
	//  (b) Use Aborted if the client should retry at a higher-level
	//      (e.g., restarting a read-modify-write sequence).
	//  (c) Use FailedPrecondition if the client should not retry until
	//      the system state has been explicitly fixed. E.g., if an "rmdir"
	//      fails because the directory is non-empty, FailedPrecondition
	//      should be returned since the client should not retry unless
	//      they have first fixed up the directory by deleting files from it.
	//  (d) Use FailedPrecondition if the client performs conditional
	//      REST Get/Update/Delete on a resource and the resource on the
	//      server does not match the condition. E.g., conflicting
	//      read-modify-write on the same resource.
	//
	// This error code will not be generated by the gRPC framework.
	FailedPrecondition Code = 9

	// Aborted indicates the operation was aborted, typically due to a
	// concurrency issue like sequencer check failures, transaction aborts,
	// etc.
	//
	// See litmus test above for deciding between FailedPrecondition,
	// Aborted, and Unavailable.
	//
	// This error code will not be generated by the gRPC framework.
	Aborted Code = 10

	// OutOfRange means operation was attempted past the valid range.
	// E.g., seeking or reading past end of file.
	//
	// Unlike InvalidArgument, this error indicates a problem that may
	// be fixed if the system state changes. For example, a 32-bit file
	// system will generate InvalidArgument if asked to read at an
	// offset that is not in the range [0,2^32-1], but it will generate
	// OutOfRange if asked to read from an offset past the current
	// file size.
	//
	// There is a fair bit of overlap between FailedPrecondition and
	// OutOfRange. We recommend using OutOfRange (the more specific
	// error) when it applies so that callers who are iterating through
	// a space can easily look for an OutOfRange error to detect when
	// they are done.
	//
	// This error code will not be generated by the gRPC framework.
	OutOfRange Code = 11

	// Unimplemented indicates operation is not implemented or not
	// supported/enabled in this service.
	//
	// This error code will be generated by the gRPC framework. Most
	// commonly, you will see this error code when a method implementation
	// is missing on the server. It can also be generated for unknown
	// compression algorithms or a disagreement as to whether an RPC should
	// be streaming.
	Unimplemented Code = 12

	// Internal errors. Means some invariants expected by underlying
	// system has been broken. If you see one of these errors,
	// something is very broken.
	//
	// This error code will be generated by the gRPC framework in several
	// internal error conditions.
	Internal Code = 13

	// Unavailable indicates the service is currently unavailable.
	// This is a most likely a transient condition and may be corrected
	// by retrying with a backoff. Note that it is not always safe to retry
	// non-idempotent operations.
	//
	// See litmus test above for deciding between FailedPrecondition,
	// Aborted, and Unavailable.
	//
	// This error code will be generated by the gRPC framework during
	// abrupt shutdown of a server process or network connection.
	Unavailable Code = 14

	// DataLoss indicates unrecoverable data loss or corruption.
	//
	// This error code will not be generated by the gRPC framework.
	DataLoss Code = 15

	// Unauthenticated indicates the request does not have valid
	// authentication credentials for the operation.
	//
	// The gRPC framework will generate this error code when the
	// authentication metadata is invalid or a Credentials callback fails,
	// but also expect authentication middleware to generate it.
	Unauthenticated Code = 16
)

func (Code) String 

func (c Code) String() string

func (*Code) UnmarshalJSON 

func (c *Code) UnmarshalJSON(b []byte) error

UnmarshalJSON unmarshals b into the Code.

type Expecter 

type Expecter interface {
	// Expect reads output from a spawned session and tries matching it with the provided regular expression.
	// It returns  all output found until match.
	Expect(*regexp.Regexp, time.Duration) (string, []string, error)
	// ExpectBatch takes an array of BatchEntries and runs through them in order. For every Expect
	// command a BatchRes entry is created with output buffer and sub matches.
	// Failure of any of the batch commands will stop the execution, returning the results up to the
	// failure.
	ExpectBatch([]Batcher, time.Duration) ([]BatchRes, error)
	// ExpectSwitchCase makes it possible to Expect with multiple regular expressions and actions. Returns the
	// full output and submatches of the commands together with an index for the matching Case.
	ExpectSwitchCase([]Caser, time.Duration) (string, []string, int, error)
	// Send sends data into the spawned session.
	Send(string) error
	// Close closes the spawned session and files.
	Close() error
}

Expecter interface primarily to make testing easier.

type GExpect 

type GExpect struct {
	// contains filtered or unexported fields
}

GExpect implements the Expecter interface.

func Spawn 

func Spawn(command string, timeout time.Duration, opts ...Option) (*GExpect, <-chan error, error)

Spawn starts a new process and collects the output. The error channel returns the result of the command Spawned when it finishes. Arguments may not contain spaces.

func SpawnFake 

func SpawnFake(b []Batcher, timeout time.Duration, opt ...Option) (*GExpect, <-chan error, error)

SpawnFake spawns an expect.Batcher.

func SpawnGeneric 

func SpawnGeneric(opt *GenOptions, timeout time.Duration, opts ...Option) (*GExpect, <-chan error, error)

SpawnGeneric is used to write generic Spawners. It returns an Expecter. The returned channel will give the return status of the spawned session, in practice this means the return value of the provided Wait function.

func SpawnSSH 

func SpawnSSH(sshClient *ssh.Client, timeout time.Duration, opts ...Option) (*GExpect, <-chan error, error)

SpawnSSH starts an interactive SSH session,ties it to a PTY and collects the output. The returned channel sends the state of the SSH session after it finishes.

func SpawnSSHPTY 

func SpawnSSHPTY(sshClient *ssh.Client, timeout time.Duration, term term.Termios, opts ...Option) (*GExpect, <-chan error, error)

SpawnSSHPTY starts an interactive SSH session and ties it to a local PTY, optionally requests a remote PTY.

func SpawnWithArgs 

func SpawnWithArgs(command []string, timeout time.Duration, opts ...Option) (*GExpect, <-chan error, error)

SpawnWithArgs starts a new process and collects the output. The error channel returns the result of the command Spawned when it finishes. Arguments may contain spaces.

func (*GExpect) Close 

func (e *GExpect) Close() error

Close closes the Spawned session.

func (*GExpect) Expect 

func (e *GExpect) Expect(re *regexp.Regexp, timeout time.Duration) (string, []string, error)

Expect reads spawned processes output looking for input regular expression. Timeout set to 0 makes Expect return the current buffer. Negative timeout value sets it to Default timeout.

func (*GExpect) ExpectBatch 

func (e *GExpect) ExpectBatch(batch []Batcher, timeout time.Duration) ([]BatchRes, error)

ExpectBatch takes an array of BatchEntry and executes them in order filling in the BatchRes array for any Expect command executed.

func (*GExpect) ExpectSwitchCase 

func (e *GExpect) ExpectSwitchCase(cs []Caser, timeout time.Duration) (string, []string, int, error)

ExpectSwitchCase checks each Case against the accumulated out buffer, sending specified string back. Leaving Send empty will Send nothing to the process. Substring expansion can be used eg. 

Case{`vf[0-9]{2}.[a-z]{3}[0-9]{2}\.net).*UP`,`show arp \1`}
Given: vf11.hnd01.net            UP      35 (4)        34 (4)          CONNECTED         0              0/0
Would send: show arp vf11.hnd01.net

func (*GExpect) Options 

func (e *GExpect) Options(opts ...Option) (prev Option)

Options sets the specified options.

func (*GExpect) Read 

func (e *GExpect) Read(p []byte) (nr int, err error)

Read implements the reader interface for the out buffer.

func (*GExpect) Send 

func (e *GExpect) Send(in string) error

Send sends a string to spawned process.

func (*GExpect) SendSignal 

func (e *GExpect) SendSignal(sig os.Signal) error

SendSignal sends a signal to the Expect controlled process. Only works on Process Expecters.

Example

ExampleGExpect_SendSignal shows the usage of the SendSignal call. 

exp, r, err := Spawn("testdata/traptest.sh", 30*time.Second)
if err != nil {
	fmt.Printf("Spawn failed: %v\n", err)
	return
}
if match, buf, err := exp.Expect(signalsInstalled, time.Second*20); err != nil {
	fmt.Printf("exp.Expect failed, match: %v, buf: %v, err: %v", match, buf, err)
	return
}

if err := exp.SendSignal(syscall.SIGUSR1); err != nil {
	fmt.Printf("exp.SendSignal failed: %v", err)
	return
}

reExpect, err := regexp.Compile("USR1")
if err != nil {
	fmt.Printf("regexp.Compile(%q) failed: %v", "Sig USR1", err)
	return
}

match, buf, err := exp.Expect(reExpect, time.Second*20)
if err != nil {
	fmt.Printf("exp.Expect failed, match: %v, buf: %v, err: %v", match, buf, err)
	return
}
fmt.Println(match)
<-r

Output:

Got the USR1 Signal

func (*GExpect) String 

func (e *GExpect) String() string

String implements the stringer interface.

type GenOptions 

type GenOptions struct {
	// In is where Expect Send messages will be written.
	In io.WriteCloser
	// Out will be read and matched by the expecter.
	Out io.Reader
	// Wait is used by expect to know when the session is over and cleanup of io Go routines should happen.
	Wait func() error
	// Close will be called as part of the expect Close, should normally include a Close of the In WriteCloser.
	Close func() error
	// Check is called everytime a Send or Expect function is called to makes sure the session is still running.
	Check func() bool
}

GenOptions contains the options needed to set up a generic Spawner.

type Option 

type Option func(*GExpect) Option

Option represents one Expecter option.

func BufferSize 

func BufferSize(bufferSize int) Option

BufferSize sets the size of receive buffer in bytes.

func ChangeCheck 

func ChangeCheck(f func() bool) Option

ChangeCheck changes the Expect check function.

Example

ExampleChangeCheck changes the check function runtime for an Expect session. 

rIn, wIn := io.Pipe()
rOut, wOut := io.Pipe()
waitCh := make(chan error)
outCh := make(chan string)
defer close(outCh)

go fakeCli(cliMap, rIn, wOut)
go func() {
	var last string
	for s := range outCh {
		if s == last {
			continue
		}
		fmt.Println(s)
		last = s
	}
}()

exp, r, err := SpawnGeneric(&GenOptions{
	In:    wIn,
	Out:   rOut,
	Wait:  func() error { return <-waitCh },
	Close: func() error { return wIn.Close() },
	Check: func() bool {
		outCh <- "Original check"
		return true
	}}, -1)
if err != nil {
	fmt.Printf("SpawnGeneric failed: %v\n", err)
	return
}
re := regexp.MustCompile("testrouter#")
interact := func() {
	for cmd := range cliMap {
		if err := exp.Send(cmd + "\n"); err != nil {
			fmt.Printf("exp.Send(%q) failed: %v\n", cmd+"\n", err)
			return
		}
		out, _, err := exp.Expect(re, -1)
		if err != nil {
			fmt.Printf("exp.Expect(%v) failed: %v out: %v", re, err, out)
			return
		}
	}
}
interact()
prev := exp.Options(ChangeCheck(func() bool {
	outCh <- "Replaced check"
	return true
}))
interact()
exp.Options(prev)
interact()

waitCh <- nil
exp.Close()
wOut.Close()

<-r

Output:

Original check
Replaced check
Original check

func CheckDuration 

func CheckDuration(d time.Duration) Option

CheckDuration changes the default duration checking for new incoming data.

func DebugCheck 

func DebugCheck(l *log.Logger) Option

DebugCheck adds logging to the check function. The check function for the spawners are called at creation/timeouts and I/O so can be usable for printing current state during debugging.

Example

ExampleDebugCheck toggles the DebugCheck option. 

rIn, wIn := io.Pipe()
rOut, wOut := io.Pipe()
rLog, wLog := io.Pipe()
waitCh := make(chan error)
defer rIn.Close()
defer wOut.Close()
defer wLog.Close()

go fakeCli(cliMap, rIn, wOut)

exp, r, err := SpawnGeneric(&GenOptions{
	In:    wIn,
	Out:   rOut,
	Wait:  func() error { return <-waitCh },
	Close: func() error { return wIn.Close() },
	Check: func() bool {
		return true
	}}, -1)
if err != nil {
	log.Printf("SpawnGeneric failed: %v", err)
	return
}
re := regexp.MustCompile("testrouter#")
interact := func() {
	for cmd := range cliMap {
		if err := exp.Send(cmd + "\n"); err != nil {
			log.Printf("exp.Send(%q) failed: %v\n", cmd+"\n", err)
			return
		}
		out, _, err := exp.Expect(re, -1)
		if err != nil {
			log.Printf("exp.Expect(%v) failed: %v out: %v", re, err, out)
			return
		}
	}
}

go func() {
	var last string
	scn := bufio.NewScanner(rLog)
	for scn.Scan() {
		ws := strings.Split(scn.Text(), " ")
		if ws[0] == last {
			continue
		}
		last = ws[0]
		fmt.Println(ws[0])
	}
}()

fmt.Println("First round")
interact()
fmt.Println("Second round - Debugging enabled")
prev := exp.Options(DebugCheck(log.New(wLog, "DebugExample ", 0)))
interact()
exp.Options(prev)
fmt.Println("Last round - Previous Check put back")
interact()

waitCh <- nil
exp.Close()
wOut.Close()

<-r

Output:

First round
Second round - Debugging enabled
DebugExample
Last round - Previous Check put back

func NoCheck 

func NoCheck() Option

NoCheck turns off the Expect alive checks.

func PartialMatch 

func PartialMatch(v bool) Option

PartialMatch enables/disables the returning of unmatched buffer so that consecutive expect call works.

func SendTimeout 

func SendTimeout(timeout time.Duration) Option

SendTimeout set timeout for Send commands

func SetEnv 

func SetEnv(env []string) Option

SetEnv sets the environmental variables of the spawned process.

func SetSysProcAttr 

func SetSysProcAttr(args *syscall.SysProcAttr) Option

SetSysProcAttr sets the SysProcAttr syscall values for the spawned process. Because this modifies cmd, it will only work with the process spawners and not effect the GExpect option method.

func Tee 

func Tee(w io.WriteCloser) Option

Tee duplicates all of the spawned process's output to the given writer and closes the writer when complete. Writes occur from another thread, so synchronization may be necessary.

func Verbose 

func Verbose(v bool) Option

Verbose enables/disables verbose logging of matches and sends.

Example

ExampleVerbose changes the Verbose and VerboseWriter options. 

rIn, wIn := io.Pipe()
rOut, wOut := io.Pipe()
waitCh := make(chan error)
outCh := make(chan string)
defer close(outCh)

go fakeCli(cliMap, rIn, wOut)
go func() {
	var last string
	for s := range outCh {
		if s == last {
			continue
		}
		fmt.Println(s)
		last = s
	}
}()

exp, r, err := SpawnGeneric(&GenOptions{
	In:    wIn,
	Out:   rOut,
	Wait:  func() error { return <-waitCh },
	Close: func() error { return wIn.Close() },
	Check: func() bool {
		return true
	}}, -1, Verbose(true), VerboseWriter(os.Stdout))
if err != nil {
	fmt.Printf("SpawnGeneric failed: %v\n", err)
	return
}
re := regexp.MustCompile("testrouter#")
var interactCmdSorted []string
for k := range cliMap {
	interactCmdSorted = append(interactCmdSorted, k)
}
sort.Strings(interactCmdSorted)
interact := func() {
	for _, cmd := range interactCmdSorted {
		if err := exp.Send(cmd + "\n"); err != nil {
			fmt.Printf("exp.Send(%q) failed: %v\n", cmd+"\n", err)
			return
		}
		out, _, err := exp.Expect(re, -1)
		if err != nil {
			fmt.Printf("exp.Expect(%v) failed: %v out: %v", re, err, out)
			return
		}
	}
}
interact()

waitCh <- nil
exp.Close()
wOut.Close()

<-r

Output:

�[34mSent:�[39m "show system uptime\n"
�[32mMatch for RE:�[39m "testrouter#" found: ["testrouter#"] Buffer: Current time:      1998-10-13 19:45:47 UTC
Time Source:       NTP CLOCK
System booted:     1998-10-12 20:51:41 UTC (22:54:06 ago)
Protocols started: 1998-10-13 19:33:45 UTC (00:12:02 ago)
Last configured:   1998-10-13 19:33:45 UTC (00:12:02 ago) by abc
12:45PM  up 22:54, 2 users, load averages: 0.07, 0.02, 0.01

testuser@testrouter#
�[34mSent:�[39m "show system users\n"
�[32mMatch for RE:�[39m "testrouter#" found: ["testrouter#"] Buffer: 7:30PM  up 4 days,  2:26, 2 users, load averages: 0.07, 0.02, 0.01
USER     TTY FROM              LOGIN@  IDLE WHAT
root     d0  -                Fri05PM 4days -csh (csh)
blue   p0 level5.company.net 7:30PM     - cli

testuser@testrouter#
�[34mSent:�[39m "show version\n"
�[32mMatch for RE:�[39m "testrouter#" found: ["testrouter#"] Buffer: Cisco IOS Software, 3600 Software (C3660-I-M), Version 12.3(4)T

TAC Support: http://www.cisco.com/tac
Copyright (c) 1986-2003 by Cisco Systems, Inc.
Compiled Thu 18-Sep-03 15:37 by ccai

ROM: System Bootstrap, Version 12.0(6r)T, RELEASE SOFTWARE (fc1)
ROM:

C3660-1 uptime is 1 week, 3 days, 6 hours, 41 minutes
System returned to ROM by power-on
System image file is "slot0:tftpboot/c3660-i-mz.123-4.T"

Cisco 3660 (R527x) processor (revision 1.0) with 57344K/8192K bytes of memory.
Processor board ID JAB055180FF
R527x CPU at 225Mhz, Implementation 40, Rev 10.0, 2048KB L2 Cache

3660 Chassis type: ENTERPRISE
2 FastEthernet interfaces
4 Serial interfaces
DRAM configuration is 64 bits wide with parity disabled.
125K bytes of NVRAM.
16384K bytes of processor board System flash (Read/Write)

Flash card inserted. Reading filesystem...done.
20480K bytes of processor board PCMCIA Slot0 flash (Read/Write)

Configuration register is 0x2102

testrouter#

func VerboseWriter 

func VerboseWriter(w io.Writer) Option

VerboseWriter sets an alternate destination for verbose logs.

type Status 

type Status struct {
	// contains filtered or unexported fields
}

Status contains an errormessage and a status code.

func NewStatus 

func NewStatus(code Code, msg string) *Status

NewStatus creates a Status with the provided code and message.

func NewStatusf 

func NewStatusf(code Code, format string, a ...interface{}) *Status

NewStatusf returns a Status with the provided code and a formatted message.

func (*Status) Err 

func (s *Status) Err() error

Err is a helper to handle errors.

func (*Status) Error 

func (s *Status) Error() string

Error is here to adhere to the error interface.

type Tag 

type Tag int32

Tag represents the state for a Caser.

type TimeoutError 

type TimeoutError int

TimeoutError is the error returned by all Expect functions upon timer expiry.

func (TimeoutError) Error 

func (t TimeoutError) Error() string

Error implements the Error interface.

Source Files

View all Source files

Directories

Path Synopsis
examples
newspawner
telnet creates a new Expect spawner for Telnet.
 telnet creates a new Expect spawner for Telnet.
process
process is a simple example of spawning a process from the expect package.
 process is a simple example of spawning a process from the expect package.

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