fix: Run expect tests on Windows with conpty pseudo-terminal (#276)

This brings together a bunch of random, partially implemented packages for support of the new(ish) Windows [`conpty`](https://devblogs.microsoft.com/commandline/windows-command-line-introducing-the-windows-pseudo-console-conpty/) API - such that we can leverage the `expect` style of CLI tests, but in a way that works in Linux/OSX `pty`s and Windows `conpty`.

These include:
- Vendoring the `go-expect` library from Netflix w/ some tweaks to work cross-platform
- Vendoring the `pty` cross-platform implementation from [waypoint-plugin-sdk](b55c787a65/internal/pkg/pty)
- Vendoring the `conpty` Windows-specific implementation from [waypoint-plugin-sdk](b55c787a65/internal/pkg/conpty)
- Adjusting the `pty` interface to work with `go-expect` + the cross-plat version

There were several limitations with the current packages:
- `go-expect` requires the same `os.File` (TTY) for input / output, but `conhost` requires separate file handles
- `conpty` does not handle input, only output
- The cross-platform `pty` didn't expose the full set of primitives needed for `console`

Therefore, the following changes were made:
- Handling of `stdin` was added to the `conpty` interface
- We weren't using the full extent of the `go-expect` interface, so some portions were removed (ie, exec'ing a process) to simplify our implementation and make it easier to extend cross-platform
- Instead of `console` exposing just a `Tty`, it exposes an `InTty` and `OutTty`, to help encapsulate the difference on Windows (on Linux, these point to the same pipe)

Future improvements:
- The `isatty` implementation doesn't support accurate detection of `conhost` pty's without an associated process. In lieu of a more robust check, I've added a `--force-tty` flag intended for test case use - that forces the CLI to run in tty mode.
- It seems the windows implementation doesn't support setting a deadline. This is needed for the expect.Timeout API, but isn't used by us yet.

Fixes #241

cli/clitest/clitest.go

@@ -2,16 +2,13 @@ package clitest
 
 import (
 	"archive/tar"
-	"bufio"
 	"bytes"
 	"errors"
 	"io"
 	"os"
 	"path/filepath"
-	"regexp"
 	"testing"
 
-	"github.com/Netflix/go-expect"
 	"github.com/spf13/cobra"
 	"github.com/stretchr/testify/require"
 
@@ -21,12 +18,6 @@ import (
 	"github.com/coder/coder/provisioner/echo"
 )
 
-var (
-	// Used to ensure terminal output doesn't have anything crazy!
-	// See: https://stackoverflow.com/a/29497680
-	stripAnsi = regexp.MustCompile("[\u001B\u009B][[\\]()#;?]*(?:(?:(?:[a-zA-Z\\d]*(?:;[a-zA-Z\\d]*)*)?\u0007)|(?:(?:\\d{1,4}(?:;\\d{0,4})*)?[\\dA-PRZcf-ntqry=><~]))")
-)
-
 // New creates a CLI instance with a configuration pointed to a
 // temporary testing directory.
 func New(t *testing.T, args ...string) (*cobra.Command, config.Root) {
@@ -55,31 +46,6 @@ func CreateProjectVersionSource(t *testing.T, responses *echo.Responses) string
 	return directory
 }
 
-// NewConsole creates a new TTY bound to the command provided.
-// All ANSI escape codes are stripped to provide clean output.
-func NewConsole(t *testing.T, cmd *cobra.Command) *expect.Console {
-	reader, writer := io.Pipe()
-	scanner := bufio.NewScanner(reader)
-	t.Cleanup(func() {
-		_ = reader.Close()
-		_ = writer.Close()
-	})
-	go func() {
-		for scanner.Scan() {
-			if scanner.Err() != nil {
-				return
-			}
-			t.Log(stripAnsi.ReplaceAllString(scanner.Text(), ""))
-		}
-	}()
-
-	console, err := expect.NewConsole(expect.WithStdout(writer))
-	require.NoError(t, err)
-	cmd.SetIn(console.Tty())
-	cmd.SetOut(console.Tty())
-	return console
-}
-
 func extractTar(t *testing.T, data []byte, directory string) {
 	reader := tar.NewReader(bytes.NewBuffer(data))
 	for {

cli/clitest/clitest_test.go

@@ -1,5 +1,3 @@
-//go:build !windows
-
 package clitest_test
 
 import (
@@ -7,6 +5,7 @@ import (
 
 	"github.com/coder/coder/cli/clitest"
 	"github.com/coder/coder/coderd/coderdtest"
+	"github.com/coder/coder/expect"
 	"github.com/stretchr/testify/require"
 	"go.uber.org/goleak"
 )
@@ -21,7 +20,7 @@ func TestCli(t *testing.T) {
 	client := coderdtest.New(t)
 	cmd, config := clitest.New(t)
 	clitest.SetupConfig(t, client, config)
-	console := clitest.NewConsole(t, cmd)
+	console := expect.NewTestConsole(t, cmd)
 	go func() {
 		err := cmd.Execute()
 		require.NoError(t, err)

cli/login.go

@@ -22,6 +22,7 @@ func login() *cobra.Command {
 		Args: cobra.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			rawURL := args[0]
+
 			if !strings.HasPrefix(rawURL, "http://") && !strings.HasPrefix(rawURL, "https://") {
 				scheme := "https"
 				if strings.HasPrefix(rawURL, "localhost") {
@@ -44,7 +45,7 @@ func login() *cobra.Command {
 				return xerrors.Errorf("has initial user: %w", err)
 			}
 			if !hasInitialUser {
-				if !isTTY(cmd.InOrStdin()) {
+				if !isTTY(cmd) {
 					return xerrors.New("the initial user cannot be created in non-interactive mode. use the API")
 				}
 				_, _ = fmt.Fprintf(cmd.OutOrStdout(), "%s Your Coder deployment hasn't been set up!\n", color.HiBlackString(">"))

cli/login_test.go

@@ -1,11 +1,10 @@
-//go:build !windows
-
 package cli_test
 
 import (
 	"testing"
 
 	"github.com/coder/coder/cli/clitest"
+	"github.com/coder/coder/expect"
 	"github.com/coder/coder/coderd/coderdtest"
 	"github.com/stretchr/testify/require"
 )
@@ -23,8 +22,11 @@ func TestLogin(t *testing.T) {
 	t.Run("InitialUserTTY", func(t *testing.T) {
 		t.Parallel()
 		client := coderdtest.New(t)
-		root, _ := clitest.New(t, "login", client.URL.String())
+		// The --force-tty flag is required on Windows, because the `isatty` library does not
-		console := clitest.NewConsole(t, root)
+		// accurately detect Windows ptys when they are not attached to a process:
+		// https://github.com/mattn/go-isatty/issues/59
+		root, _ := clitest.New(t, "login", client.URL.String(), "--force-tty")
+		console := expect.NewTestConsole(t, root)
 		go func() {
 			err := root.Execute()
 			require.NoError(t, err)

cli/projectcreate_test.go

@@ -1,5 +1,3 @@
-//go:build !windows
-
 package cli_test
 
 import (
@@ -10,6 +8,7 @@ import (
 	"github.com/coder/coder/cli/clitest"
 	"github.com/coder/coder/coderd/coderdtest"
 	"github.com/coder/coder/database"
+	"github.com/coder/coder/expect"
 	"github.com/coder/coder/provisioner/echo"
 	"github.com/coder/coder/provisionersdk/proto"
 )
@@ -27,7 +26,7 @@ func TestProjectCreate(t *testing.T) {
 		cmd, root := clitest.New(t, "projects", "create", "--directory", source, "--provisioner", string(database.ProvisionerTypeEcho))
 		clitest.SetupConfig(t, client, root)
 		_ = coderdtest.NewProvisionerDaemon(t, client)
-		console := clitest.NewConsole(t, cmd)
+		console := expect.NewTestConsole(t, cmd)
 		closeChan := make(chan struct{})
 		go func() {
 			err := cmd.Execute()
@@ -74,7 +73,7 @@ func TestProjectCreate(t *testing.T) {
 		cmd, root := clitest.New(t, "projects", "create", "--directory", source, "--provisioner", string(database.ProvisionerTypeEcho))
 		clitest.SetupConfig(t, client, root)
 		coderdtest.NewProvisionerDaemon(t, client)
-		console := clitest.NewConsole(t, cmd)
+		console := expect.NewTestConsole(t, cmd)
 		closeChan := make(chan struct{})
 		go func() {
 			err := cmd.Execute()

cli/root.go

@@ -21,6 +21,7 @@ import (
 
 const (
 	varGlobalConfig = "global-config"
+	varForceTty     = "force-tty"
 )
 
 func Root() *cobra.Command {
@@ -65,6 +66,12 @@ func Root() *cobra.Command {
 	cmd.AddCommand(users())
 
 	cmd.PersistentFlags().String(varGlobalConfig, configdir.LocalConfig("coder"), "Path to the global `coder` config directory")
+	cmd.PersistentFlags().Bool(varForceTty, false, "Force the `coder` command to run as if connected to a TTY")
+	err := cmd.PersistentFlags().MarkHidden(varForceTty)
+	if err != nil {
+		// This should never return an error, because we just added the `--force-tty`` flag prior to calling MarkHidden.
+		panic(err)
+	}
 
 	return cmd
 }
@@ -113,7 +120,16 @@ func createConfig(cmd *cobra.Command) config.Root {
 // isTTY returns whether the passed reader is a TTY or not.
 // This accepts a reader to work with Cobra's "InOrStdin"
 // function for simple testing.
-func isTTY(reader io.Reader) bool {
+func isTTY(cmd *cobra.Command) bool {
+	// If the `--force-tty` command is available, and set,
+	// assume we're in a tty. This is primarily for cases on Windows
+	// where we may not be able to reliably detect this automatically (ie, tests)
+	forceTty, err := cmd.Flags().GetBool(varForceTty)
+	if forceTty && err == nil {
+		return true
+	}
+
+	reader := cmd.InOrStdin()
 	file, ok := reader.(*os.File)
 	if !ok {
 		return false

cli/workspacecreate_test.go

@@ -1,5 +1,3 @@
-//go:build !windows
-
 package cli_test
 
 import (
@@ -7,6 +5,7 @@ import (
 
 	"github.com/coder/coder/cli/clitest"
 	"github.com/coder/coder/coderd/coderdtest"
+	"github.com/coder/coder/expect"
 	"github.com/coder/coder/provisioner/echo"
 	"github.com/coder/coder/provisionersdk/proto"
 	"github.com/stretchr/testify/require"
@@ -37,7 +36,7 @@ func TestWorkspaceCreate(t *testing.T) {
 		cmd, root := clitest.New(t, "workspaces", "create", project.Name)
 		clitest.SetupConfig(t, client, root)
 
-		console := clitest.NewConsole(t, cmd)
+		console := expect.NewTestConsole(t, cmd)
 		closeChan := make(chan struct{})
 		go func() {
 			err := cmd.Execute()

expect/conpty/conpty.go

@@ -0,0 +1,107 @@
+//go:build windows
+// +build windows
+
+// Original copyright 2020 ActiveState Software. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file
+
+package conpty
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"golang.org/x/sys/windows"
+)
+
+// ConPty represents a windows pseudo console.
+type ConPty struct {
+	hpCon                    windows.Handle
+	outPipePseudoConsoleSide windows.Handle
+	outPipeOurSide           windows.Handle
+	inPipeOurSide            windows.Handle
+	inPipePseudoConsoleSide  windows.Handle
+	consoleSize              uintptr
+	outFilePseudoConsoleSide *os.File
+	outFileOurSide           *os.File
+	inFilePseudoConsoleSide  *os.File
+	inFileOurSide            *os.File
+	closed                   bool
+}
+
+// New returns a new ConPty pseudo terminal device
+func New(columns int16, rows int16) (*ConPty, error) {
+	c := &ConPty{
+		consoleSize: uintptr(columns) + (uintptr(rows) << 16),
+	}
+
+	return c, c.createPseudoConsoleAndPipes()
+}
+
+// Close closes the pseudo-terminal and cleans up all attached resources
+func (c *ConPty) Close() error {
+	// Trying to close these pipes multiple times will result in an
+	// access violation
+	if c.closed {
+		return nil
+	}
+
+	err := closePseudoConsole(c.hpCon)
+	c.outFilePseudoConsoleSide.Close()
+	c.outFileOurSide.Close()
+	c.inFilePseudoConsoleSide.Close()
+	c.inFileOurSide.Close()
+	c.closed = true
+	return err
+}
+
+// OutPipe returns the output pipe of the pseudo terminal
+func (c *ConPty) OutPipe() *os.File {
+	return c.outFilePseudoConsoleSide
+}
+
+func (c *ConPty) Reader() io.Reader {
+	return c.outFileOurSide
+}
+
+// InPipe returns input pipe of the pseudo terminal
+// Note: It is safer to use the Write method to prevent partially-written VT sequences
+// from corrupting the terminal
+func (c *ConPty) InPipe() *os.File {
+	return c.inFilePseudoConsoleSide
+}
+
+func (c *ConPty) WriteString(str string) (int, error) {
+	return c.inFileOurSide.WriteString(str)
+}
+
+func (c *ConPty) createPseudoConsoleAndPipes() error {
+	// Create the stdin pipe
+	if err := windows.CreatePipe(&c.inPipePseudoConsoleSide, &c.inPipeOurSide, nil, 0); err != nil {
+		return err
+	}
+
+	// Create the stdout pipe
+	if err := windows.CreatePipe(&c.outPipeOurSide, &c.outPipePseudoConsoleSide, nil, 0); err != nil {
+		return err
+	}
+
+	// Create the pty with our stdin/stdout
+	if err := createPseudoConsole(c.consoleSize, c.inPipePseudoConsoleSide, c.outPipePseudoConsoleSide, &c.hpCon); err != nil {
+		return fmt.Errorf("failed to create pseudo console: %d, %v", uintptr(c.hpCon), err)
+	}
+
+	c.outFilePseudoConsoleSide = os.NewFile(uintptr(c.outPipePseudoConsoleSide), "|0")
+	c.outFileOurSide = os.NewFile(uintptr(c.outPipeOurSide), "|1")
+
+	c.inFilePseudoConsoleSide = os.NewFile(uintptr(c.inPipePseudoConsoleSide), "|2")
+	c.inFileOurSide = os.NewFile(uintptr(c.inPipeOurSide), "|3")
+	c.closed = false
+
+	return nil
+}
+
+func (c *ConPty) Resize(cols uint16, rows uint16) error {
+	return resizePseudoConsole(c.hpCon, uintptr(cols)+(uintptr(rows)<<16))
+}

expect/conpty/syscall.go

@@ -0,0 +1,53 @@
+//go:build windows
+// +build windows
+
+// Copyright 2020 ActiveState Software. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file
+
+package conpty
+
+import (
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+var (
+	kernel32                = windows.NewLazySystemDLL("kernel32.dll")
+	procResizePseudoConsole = kernel32.NewProc("ResizePseudoConsole")
+	procCreatePseudoConsole = kernel32.NewProc("CreatePseudoConsole")
+	procClosePseudoConsole  = kernel32.NewProc("ClosePseudoConsole")
+)
+
+func createPseudoConsole(consoleSize uintptr, ptyIn windows.Handle, ptyOut windows.Handle, hpCon *windows.Handle) (err error) {
+	r1, _, e1 := procCreatePseudoConsole.Call(
+		consoleSize,
+		uintptr(ptyIn),
+		uintptr(ptyOut),
+		0,
+		uintptr(unsafe.Pointer(hpCon)),
+	)
+
+	if r1 != 0 { // !S_OK
+		err = e1
+	}
+	return
+}
+
+func resizePseudoConsole(handle windows.Handle, consoleSize uintptr) (err error) {
+	r1, _, e1 := procResizePseudoConsole.Call(uintptr(handle), consoleSize)
+	if r1 != 0 { // !S_OK
+		err = e1
+	}
+	return
+}
+
+func closePseudoConsole(handle windows.Handle) (err error) {
+	r1, _, e1 := procClosePseudoConsole.Call(uintptr(handle))
+	if r1 == 0 {
+		err = e1
+	}
+
+	return
+}

expect/console.go

@@ -0,0 +1,163 @@
+// Copyright 2018 Netflix, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package expect
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"unicode/utf8"
+
+	"github.com/coder/coder/expect/pty"
+)
+
+// Console is an interface to automate input and output for interactive
+// applications. Console can block until a specified output is received and send
+// input back on it's tty. Console can also multiplex other sources of input
+// and multiplex its output to other writers.
+type Console struct {
+	opts       ConsoleOpts
+	pty        pty.Pty
+	runeReader *bufio.Reader
+	closers    []io.Closer
+}
+
+// ConsoleOpt allows setting Console options.
+type ConsoleOpt func(*ConsoleOpts) error
+
+// ConsoleOpts provides additional options on creating a Console.
+type ConsoleOpts struct {
+	Logger          *log.Logger
+	Stdouts         []io.Writer
+	ExpectObservers []Observer
+}
+
+// Observer provides an interface for a function callback that will
+// be called after each Expect operation.
+// matchers will be the list of active matchers when an error occurred,
+//   or a list of matchers that matched `buf` when err is nil.
+// buf is the captured output that was matched against.
+// err is error that might have occurred. May be nil.
+type Observer func(matchers []Matcher, buf string, err error)
+
+// WithStdout adds writers that Console duplicates writes to, similar to the
+// Unix tee(1) command.
+//
+// Each write is written to each listed writer, one at a time. Console is the
+// last writer, writing to it's internal buffer for matching expects.
+// If a listed writer returns an error, that overall write operation stops and
+// returns the error; it does not continue down the list.
+func WithStdout(writers ...io.Writer) ConsoleOpt {
+	return func(opts *ConsoleOpts) error {
+		opts.Stdouts = append(opts.Stdouts, writers...)
+		return nil
+	}
+}
+
+// WithLogger adds a logger for Console to log debugging information to. By
+// default Console will discard logs.
+func WithLogger(logger *log.Logger) ConsoleOpt {
+	return func(opts *ConsoleOpts) error {
+		opts.Logger = logger
+		return nil
+	}
+}
+
+// WithExpectObserver adds an ExpectObserver to allow monitoring Expect operations.
+func WithExpectObserver(observers ...Observer) ConsoleOpt {
+	return func(opts *ConsoleOpts) error {
+		opts.ExpectObservers = append(opts.ExpectObservers, observers...)
+		return nil
+	}
+}
+
+// NewConsole returns a new Console with the given options.
+func NewConsole(opts ...ConsoleOpt) (*Console, error) {
+	options := ConsoleOpts{
+		Logger: log.New(ioutil.Discard, "", 0),
+	}
+
+	for _, opt := range opts {
+		if err := opt(&options); err != nil {
+			return nil, err
+		}
+	}
+
+	consolePty, err := pty.New()
+	if err != nil {
+		return nil, err
+	}
+	closers := []io.Closer{consolePty}
+	reader := consolePty.Reader()
+
+	console := &Console{
+		opts:       options,
+		pty:        consolePty,
+		runeReader: bufio.NewReaderSize(reader, utf8.UTFMax),
+		closers:    closers,
+	}
+
+	return console, nil
+}
+
+// Tty returns an input Tty for accepting input
+func (c *Console) InTty() *os.File {
+	return c.pty.InPipe()
+}
+
+// OutTty returns an output tty for writing
+func (c *Console) OutTty() *os.File {
+	return c.pty.OutPipe()
+}
+
+// Close closes Console's tty. Calling Close will unblock Expect and ExpectEOF.
+func (c *Console) Close() error {
+	for _, fd := range c.closers {
+		err := fd.Close()
+		if err != nil {
+			c.Logf("failed to close: %s", err)
+		}
+	}
+	return nil
+}
+
+// Send writes string s to Console's tty.
+func (c *Console) Send(s string) (int, error) {
+	c.Logf("console send: %q", s)
+	n, err := c.pty.WriteString(s)
+	return n, err
+}
+
+// SendLine writes string s to Console's tty with a trailing newline.
+func (c *Console) SendLine(s string) (int, error) {
+	bytes, err := c.Send(fmt.Sprintf("%s\n", s))
+
+	return bytes, err
+}
+
+// Log prints to Console's logger.
+// Arguments are handled in the manner of fmt.Print.
+func (c *Console) Log(v ...interface{}) {
+	c.opts.Logger.Print(v...)
+}
+
+// Logf prints to Console's logger.
+// Arguments are handled in the manner of fmt.Printf.
+func (c *Console) Logf(format string, v ...interface{}) {
+	c.opts.Logger.Printf(format, v...)
+}

expect/doc.go

@@ -0,0 +1,19 @@
+// Copyright 2018 Netflix, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package expect provides an expect-like interface to automate control of
+// applications. It is unlike expect in that it does not spawn or manage
+// process lifecycle. This package only focuses on expecting output and sending
+// input through it's psuedoterminal.
+package expect

expect/expect.go

@@ -0,0 +1,109 @@
+// Copyright 2018 Netflix, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package expect
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"unicode/utf8"
+)
+
+// Expectf reads from the Console's tty until the provided formatted string
+// is read or an error occurs, and returns the buffer read by Console.
+func (c *Console) Expectf(format string, args ...interface{}) (string, error) {
+	return c.Expect(String(fmt.Sprintf(format, args...)))
+}
+
+// ExpectString reads from Console's tty until the provided string is read or
+// an error occurs, and returns the buffer read by Console.
+func (c *Console) ExpectString(s string) (string, error) {
+	return c.Expect(String(s))
+}
+
+// Expect reads from Console's tty until a condition specified from opts is
+// encountered or an error occurs, and returns the buffer read by console.
+// No extra bytes are read once a condition is met, so if a program isn't
+// expecting input yet, it will be blocked. Sends are queued up in tty's
+// internal buffer so that the next Expect will read the remaining bytes (i.e.
+// rest of prompt) as well as its conditions.
+func (c *Console) Expect(opts ...Opt) (string, error) {
+	var options Opts
+	for _, opt := range opts {
+		if err := opt(&options); err != nil {
+			return "", err
+		}
+	}
+
+	buf := new(bytes.Buffer)
+	writer := io.MultiWriter(append(c.opts.Stdouts, buf)...)
+	runeWriter := bufio.NewWriterSize(writer, utf8.UTFMax)
+
+	var matcher Matcher
+	var err error
+
+	defer func() {
+		for _, observer := range c.opts.ExpectObservers {
+			if matcher != nil {
+				observer([]Matcher{matcher}, buf.String(), err)
+				return
+			}
+			observer(options.Matchers, buf.String(), err)
+		}
+	}()
+
+	for {
+		var r rune
+		r, _, err = c.runeReader.ReadRune()
+		if err != nil {
+			matcher = options.Match(err)
+			if matcher != nil {
+				err = nil
+				break
+			}
+			return buf.String(), err
+		}
+
+		c.Logf("expect read: %q", string(r))
+		_, err = runeWriter.WriteRune(r)
+		if err != nil {
+			return buf.String(), err
+		}
+
+		// Immediately flush rune to the underlying writers.
+		err = runeWriter.Flush()
+		if err != nil {
+			return buf.String(), err
+		}
+
+		matcher = options.Match(buf)
+		if matcher != nil {
+			break
+		}
+	}
+
+	if matcher != nil {
+		cb, ok := matcher.(CallbackMatcher)
+		if ok {
+			err = cb.Callback(buf)
+			if err != nil {
+				return buf.String(), err
+			}
+		}
+	}
+
+	return buf.String(), err
+}

expect/expect_opt.go

@@ -0,0 +1,139 @@
+// Copyright 2018 Netflix, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package expect
+
+import (
+	"bytes"
+	"strings"
+	"time"
+)
+
+// Opt allows settings Expect options.
+type Opt func(*Opts) error
+
+// ConsoleCallback is a callback function to execute if a match is found for
+// the chained matcher.
+type ConsoleCallback func(buf *bytes.Buffer) error
+
+// Opts provides additional options on Expect.
+type Opts struct {
+	Matchers    []Matcher
+	ReadTimeout *time.Duration
+}
+
+// Match sequentially calls Match on all matchers in ExpectOpts and returns the
+// first matcher if a match exists, otherwise nil.
+func (eo Opts) Match(v interface{}) Matcher {
+	for _, matcher := range eo.Matchers {
+		if matcher.Match(v) {
+			return matcher
+		}
+	}
+	return nil
+}
+
+// CallbackMatcher is a matcher that provides a Callback function.
+type CallbackMatcher interface {
+	// Callback executes the matcher's callback with the content buffer at the
+	// time of match.
+	Callback(buf *bytes.Buffer) error
+}
+
+// Matcher provides an interface for finding a match in content read from
+// Console's tty.
+type Matcher interface {
+	// Match returns true iff a match is found.
+	Match(v interface{}) bool
+	Criteria() interface{}
+}
+
+// stringMatcher fulfills the Matcher interface to match strings against a given
+// bytes.Buffer.
+type stringMatcher struct {
+	str string
+}
+
+func (sm *stringMatcher) Match(v interface{}) bool {
+	buf, ok := v.(*bytes.Buffer)
+	if !ok {
+		return false
+	}
+	if strings.Contains(buf.String(), sm.str) {
+		return true
+	}
+	return false
+}
+
+func (sm *stringMatcher) Criteria() interface{} {
+	return sm.str
+}
+
+// allMatcher fulfills the Matcher interface to match a group of ExpectOpt
+// against any value.
+type allMatcher struct {
+	options Opts
+}
+
+func (am *allMatcher) Match(v interface{}) bool {
+	var matchers []Matcher
+	for _, matcher := range am.options.Matchers {
+		if matcher.Match(v) {
+			continue
+		}
+		matchers = append(matchers, matcher)
+	}
+
+	am.options.Matchers = matchers
+	return len(matchers) == 0
+}
+
+func (am *allMatcher) Criteria() interface{} {
+	var criteria []interface{}
+	for _, matcher := range am.options.Matchers {
+		criteria = append(criteria, matcher.Criteria())
+	}
+	return criteria
+}
+
+// All adds an Expect condition to exit if the content read from Console's tty
+// matches all of the provided ExpectOpt, in any order.
+func All(expectOpts ...Opt) Opt {
+	return func(opts *Opts) error {
+		var options Opts
+		for _, opt := range expectOpts {
+			if err := opt(&options); err != nil {
+				return err
+			}
+		}
+
+		opts.Matchers = append(opts.Matchers, &allMatcher{
+			options: options,
+		})
+		return nil
+	}
+}
+
+// String adds an Expect condition to exit if the content read from Console's
+// tty contains any of the given strings.
+func String(strs ...string) Opt {
+	return func(opts *Opts) error {
+		for _, str := range strs {
+			opts.Matchers = append(opts.Matchers, &stringMatcher{
+				str: str,
+			})
+		}
+		return nil
+	}
+}

expect/expect_opt_test.go

@@ -0,0 +1,163 @@
+// Copyright 2018 Netflix, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package expect_test
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	. "github.com/coder/coder/expect"
+)
+
+func TestExpectOptString(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		title    string
+		opt      Opt
+		data     string
+		expected bool
+	}{
+		{
+			"No args",
+			String(),
+			"Hello world",
+			false,
+		},
+		{
+			"Single arg",
+			String("Hello"),
+			"Hello world",
+			true,
+		},
+		{
+			"Multiple arg",
+			String("other", "world"),
+			"Hello world",
+			true,
+		},
+		{
+			"No matches",
+			String("hello"),
+			"Hello world",
+			false,
+		},
+	}
+
+	for _, test := range tests {
+		test := test
+		t.Run(test.title, func(t *testing.T) {
+			t.Parallel()
+
+			var options Opts
+			err := test.opt(&options)
+			require.Nil(t, err)
+
+			buf := new(bytes.Buffer)
+			_, err = buf.WriteString(test.data)
+			require.Nil(t, err)
+
+			matcher := options.Match(buf)
+			if test.expected {
+				require.NotNil(t, matcher)
+			} else {
+				require.Nil(t, matcher)
+			}
+		})
+	}
+}
+
+func TestExpectOptAll(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		title    string
+		opt      Opt
+		data     string
+		expected bool
+	}{
+		{
+			"No opts",
+			All(),
+			"Hello world",
+			true,
+		},
+		{
+			"Single string match",
+			All(String("Hello")),
+			"Hello world",
+			true,
+		},
+		{
+			"Single string no match",
+			All(String("Hello")),
+			"No match",
+			false,
+		},
+		{
+			"Ordered strings match",
+			All(String("Hello"), String("world")),
+			"Hello world",
+			true,
+		},
+		{
+			"Ordered strings not all match",
+			All(String("Hello"), String("world")),
+			"Hello",
+			false,
+		},
+		{
+			"Unordered strings",
+			All(String("world"), String("Hello")),
+			"Hello world",
+			true,
+		},
+		{
+			"Unordered strings not all match",
+			All(String("world"), String("Hello")),
+			"Hello",
+			false,
+		},
+		{
+			"Repeated strings match",
+			All(String("Hello"), String("Hello")),
+			"Hello world",
+			true,
+		},
+	}
+
+	for _, test := range tests {
+		test := test
+		t.Run(test.title, func(t *testing.T) {
+			t.Parallel()
+			var options Opts
+			err := test.opt(&options)
+			require.Nil(t, err)
+
+			buf := new(bytes.Buffer)
+			_, err = buf.WriteString(test.data)
+			require.Nil(t, err)
+
+			matcher := options.Match(buf)
+			if test.expected {
+				require.NotNil(t, matcher)
+			} else {
+				require.Nil(t, matcher)
+			}
+		})
+	}
+}

expect/expect_test.go

@@ -0,0 +1,181 @@
+// Copyright 2018 Netflix, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package expect_test
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"runtime/debug"
+	"strings"
+	"sync"
+	"testing"
+
+	"golang.org/x/xerrors"
+
+	. "github.com/coder/coder/expect"
+)
+
+var (
+	ErrWrongAnswer = xerrors.New("wrong answer")
+)
+
+type Survey struct {
+	Prompt string
+	Answer string
+}
+
+func Prompt(in io.Reader, out io.Writer) error {
+	reader := bufio.NewReader(in)
+
+	for _, survey := range []Survey{
+		{
+			"What is 1+1?", "2",
+		},
+		{
+			"What is Netflix backwards?", "xilfteN",
+		},
+	} {
+		_, err := fmt.Fprintf(out, "%s: ", survey.Prompt)
+		if err != nil {
+			return err
+		}
+		text, err := reader.ReadString('\n')
+		if err != nil {
+			return err
+		}
+
+		_, err = fmt.Fprint(out, text)
+		if err != nil {
+			return err
+		}
+		text = strings.TrimSpace(text)
+		if text != survey.Answer {
+			return ErrWrongAnswer
+		}
+	}
+
+	return nil
+}
+
+func newTestConsole(t *testing.T, opts ...ConsoleOpt) (*Console, error) {
+	opts = append([]ConsoleOpt{
+		expectNoError(t),
+	}, opts...)
+	return NewConsole(opts...)
+}
+
+func expectNoError(t *testing.T) ConsoleOpt {
+	return WithExpectObserver(
+		func(matchers []Matcher, buf string, err error) {
+			if err == nil {
+				return
+			}
+			if len(matchers) == 0 {
+				t.Fatalf("Error occurred while matching %q: %s\n%s", buf, err, string(debug.Stack()))
+			} else {
+				var criteria []string
+				for _, matcher := range matchers {
+					criteria = append(criteria, fmt.Sprintf("%q", matcher.Criteria()))
+				}
+				t.Fatalf("Failed to find [%s] in %q: %s\n%s", strings.Join(criteria, ", "), buf, err, string(debug.Stack()))
+			}
+		},
+	)
+}
+
+func testCloser(t *testing.T, closer io.Closer) {
+	if err := closer.Close(); err != nil {
+		t.Errorf("Close failed: %s", err)
+		debug.PrintStack()
+	}
+}
+
+func TestExpectf(t *testing.T) {
+	t.Parallel()
+
+	console, err := newTestConsole(t)
+	if err != nil {
+		t.Errorf("Expected no error but got'%s'", err)
+	}
+	defer testCloser(t, console)
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		console.Expectf("What is 1+%d?", 1)
+		console.SendLine("2")
+		console.Expectf("What is %s backwards?", "Netflix")
+		console.SendLine("xilfteN")
+	}()
+
+	err = Prompt(console.InTty(), console.OutTty())
+	if err != nil {
+		t.Errorf("Expected no error but got '%s'", err)
+	}
+	wg.Wait()
+}
+
+func TestExpect(t *testing.T) {
+	t.Parallel()
+
+	console, err := newTestConsole(t)
+	if err != nil {
+		t.Errorf("Expected no error but got'%s'", err)
+	}
+	defer testCloser(t, console)
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		console.ExpectString("What is 1+1?")
+		console.SendLine("2")
+		console.ExpectString("What is Netflix backwards?")
+		console.SendLine("xilfteN")
+	}()
+
+	err = Prompt(console.InTty(), console.OutTty())
+	if err != nil {
+		t.Errorf("Expected no error but got '%s'", err)
+	}
+	wg.Wait()
+}
+
+func TestExpectOutput(t *testing.T) {
+	t.Parallel()
+
+	console, err := newTestConsole(t)
+	if err != nil {
+		t.Errorf("Expected no error but got'%s'", err)
+	}
+	defer testCloser(t, console)
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		console.ExpectString("What is 1+1?")
+		console.SendLine("3")
+	}()
+
+	err = Prompt(console.InTty(), console.OutTty())
+	if err == nil || !errors.Is(err, ErrWrongAnswer) {
+		t.Errorf("Expected error '%s' but got '%s' instead", ErrWrongAnswer, err)
+	}
+	wg.Wait()
+}

expect/pty/pty.go

@@ -0,0 +1,21 @@
+package pty
+
+import (
+	"io"
+	"os"
+)
+
+// Pty is the minimal pseudo-tty interface we require.
+type Pty interface {
+	InPipe() *os.File
+	OutPipe() *os.File
+	Resize(cols uint16, rows uint16) error
+	WriteString(str string) (int, error)
+	Reader() io.Reader
+	Close() error
+}
+
+// New creates a new Pty.
+func New() (Pty, error) {
+	return newPty()
+}

expect/pty/pty_other.go

@@ -0,0 +1,63 @@
+//go:build !windows
+// +build !windows
+
+package pty
+
+import (
+	"io"
+	"os"
+
+	"github.com/creack/pty"
+)
+
+func newPty() (Pty, error) {
+	ptyFile, ttyFile, err := pty.Open()
+	if err != nil {
+		return nil, err
+	}
+
+	return &unixPty{
+		pty: ptyFile,
+		tty: ttyFile,
+	}, nil
+}
+
+type unixPty struct {
+	pty, tty *os.File
+}
+
+func (p *unixPty) InPipe() *os.File {
+	return p.tty
+}
+
+func (p *unixPty) OutPipe() *os.File {
+	return p.tty
+}
+
+func (p *unixPty) Reader() io.Reader {
+	return p.pty
+}
+
+func (p *unixPty) WriteString(str string) (int, error) {
+	return p.pty.WriteString(str)
+}
+
+func (p *unixPty) Resize(cols uint16, rows uint16) error {
+	return pty.Setsize(p.tty, &pty.Winsize{
+		Rows: rows,
+		Cols: cols,
+	})
+}
+
+func (p *unixPty) Close() error {
+	err := p.pty.Close()
+	if err != nil {
+		return err
+	}
+
+	err = p.tty.Close()
+	if err != nil {
+		return err
+	}
+	return nil
+}

expect/pty/pty_windows.go

@@ -0,0 +1,78 @@
+//go:build windows
+// +build windows
+
+package pty
+
+import (
+	"io"
+	"os"
+
+	"golang.org/x/sys/windows"
+
+	"github.com/coder/coder/expect/conpty"
+)
+
+func newPty() (Pty, error) {
+	// We use the CreatePseudoConsole API which was introduced in build 17763
+	vsn := windows.RtlGetVersion()
+	if vsn.MajorVersion < 10 ||
+		vsn.BuildNumber < 17763 {
+		// If the CreatePseudoConsole API is not available, we fall back to a simpler
+		// implementation that doesn't create an actual PTY - just uses os.Pipe
+		return pipePty()
+	}
+
+	return conpty.New(80, 80)
+}
+
+func pipePty() (Pty, error) {
+	inFilePipeSide, inFileOurSide, err := os.Pipe()
+	if err != nil {
+		return nil, err
+	}
+
+	outFileOurSide, outFilePipeSide, err := os.Pipe()
+	if err != nil {
+		return nil, err
+	}
+
+	return &pipePtyVal{
+		inFilePipeSide,
+		inFileOurSide,
+		outFileOurSide,
+		outFilePipeSide,
+	}, nil
+}
+
+type pipePtyVal struct {
+	inFilePipeSide, inFileOurSide   *os.File
+	outFileOurSide, outFilePipeSide *os.File
+}
+
+func (p *pipePtyVal) InPipe() *os.File {
+	return p.inFilePipeSide
+}
+
+func (p *pipePtyVal) OutPipe() *os.File {
+	return p.outFilePipeSide
+}
+
+func (p *pipePtyVal) Reader() io.Reader {
+	return p.outFileOurSide
+}
+
+func (p *pipePtyVal) WriteString(str string) (int, error) {
+	return p.inFileOurSide.WriteString(str)
+}
+
+func (p *pipePtyVal) Resize(uint16, uint16) error {
+	return nil
+}
+
+func (p *pipePtyVal) Close() error {
+	p.inFileOurSide.Close()
+	p.inFilePipeSide.Close()
+	p.outFilePipeSide.Close()
+	p.outFileOurSide.Close()
+	return nil
+}

expect/test_console.go

@@ -0,0 +1,45 @@
+package expect
+
+import (
+	"bufio"
+	"io"
+	"regexp"
+	"testing"
+
+	"github.com/spf13/cobra"
+	"github.com/stretchr/testify/require"
+)
+
+var (
+	// Used to ensure terminal output doesn't have anything crazy!
+	// See: https://stackoverflow.com/a/29497680
+	stripAnsi = regexp.MustCompile("[\u001B\u009B][[\\]()#;?]*(?:(?:(?:[a-zA-Z\\d]*(?:;[a-zA-Z\\d]*)*)?\u0007)|(?:(?:\\d{1,4}(?:;\\d{0,4})*)?[\\dA-PRZcf-ntqry=><~]))")
+)
+
+// NewTestConsole creates a new TTY bound to the command provided.
+// All ANSI escape codes are stripped to provide clean output.
+func NewTestConsole(t *testing.T, cmd *cobra.Command) *Console {
+	reader, writer := io.Pipe()
+	scanner := bufio.NewScanner(reader)
+	t.Cleanup(func() {
+		_ = reader.Close()
+		_ = writer.Close()
+	})
+	go func() {
+		for scanner.Scan() {
+			if scanner.Err() != nil {
+				return
+			}
+			t.Log(stripAnsi.ReplaceAllString(scanner.Text(), ""))
+		}
+	}()
+
+	console, err := NewConsole(WithStdout(writer))
+	require.NoError(t, err)
+	t.Cleanup(func() {
+		console.Close()
+	})
+	cmd.SetIn(console.InTty())
+	cmd.SetOut(console.OutTty())
+	return console
+}