fix: Rewrite ptytest to buffer stdout (#3170)

mafredri · web-flow · commit 92a95fbd5f04 · 2022-07-25T20:02:34.000+03:00
Fixes #2122
diff --git a/pty/ptytest/ptytest.go b/pty/ptytest/ptytest.go
@@ -7,116 +7,239 @@ import (
 	"io"
 	"os"
 	"os/exec"
-	"regexp"
 	"runtime"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 	"unicode/utf8"
 
 	"github.com/stretchr/testify/require"
+	"golang.org/x/xerrors"
 
 	"github.com/coder/coder/pty"
 )
 
-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=><~]))")
-)
-
 func New(t *testing.T) *PTY {
 	ptty, err := pty.New()
 	require.NoError(t, err)
 
-	return create(t, ptty)
+	return create(t, ptty, "cmd")
 }
 
 func Start(t *testing.T, cmd *exec.Cmd) (*PTY, *os.Process) {
 	ptty, ps, err := pty.Start(cmd)
 	require.NoError(t, err)
-	return create(t, ptty), ps
+	return create(t, ptty, cmd.Args[0]), ps
 }
 
-func create(t *testing.T, ptty pty.PTY) *PTY {
-	reader, writer := io.Pipe()
-	scanner := bufio.NewScanner(reader)
+func create(t *testing.T, ptty pty.PTY, name string) *PTY {
+	// Use pipe for logging.
+	logDone := make(chan struct{})
+	logr, logw := io.Pipe()
 	t.Cleanup(func() {
-		_ = reader.Close()
-		_ = writer.Close()
+		_ = logw.Close()
+		_ = logr.Close()
+		<-logDone // Guard against logging after test.
 	})
 	go func() {
-		for scanner.Scan() {
-			if scanner.Err() != nil {
-				return
-			}
-			t.Log(stripAnsi.ReplaceAllString(scanner.Text(), ""))
+		defer close(logDone)
+		s := bufio.NewScanner(logr)
+		for s.Scan() {
+			// Quote output to avoid terminal escape codes, e.g. bell.
+			t.Logf("%s: stdout: %q", name, s.Text())
 		}
 	}()
 
+	// Write to log and output buffer.
+	copyDone := make(chan struct{})
+	out := newStdbuf()
+	w := io.MultiWriter(logw, out)
+	go func() {
+		defer close(copyDone)
+		_, err := io.Copy(w, ptty.Output())
+		_ = out.closeErr(err)
+	}()
 	t.Cleanup(func() {
+		_ = out.Close
 		_ = ptty.Close()
+		<-copyDone
 	})
+
 	return &PTY{
 		t:   t,
 		PTY: ptty,
+		out: out,
 
-		outputWriter: writer,
-		runeReader:   bufio.NewReaderSize(ptty.Output(), utf8.UTFMax),
+		runeReader: bufio.NewReaderSize(out, utf8.UTFMax),
 	}
 }
 
 type PTY struct {
 	t *testing.T
 	pty.PTY
+	out *stdbuf
 
-	outputWriter io.Writer
-	runeReader   *bufio.Reader
+	runeReader *bufio.Reader
 }
 
 func (p *PTY) ExpectMatch(str string) string {
+	p.t.Helper()
+
+	timeout, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
 	var buffer bytes.Buffer
-	multiWriter := io.MultiWriter(&buffer, p.outputWriter)
-	runeWriter := bufio.NewWriterSize(multiWriter, utf8.UTFMax)
-	complete, cancelFunc := context.WithCancel(context.Background())
-	defer cancelFunc()
+	match := make(chan error, 1)
 	go func() {
-		timer := time.NewTimer(10 * time.Second)
-		defer timer.Stop()
-		select {
-		case <-complete.Done():
-			return
-		case <-timer.C:
-		}
-		_ = p.Close()
-		p.t.Errorf("%s match exceeded deadline: wanted %q; got %q", time.Now(), str, buffer.String())
+		defer close(match)
+		match <- func() error {
+			for {
+				r, _, err := p.runeReader.ReadRune()
+				if err != nil {
+					return err
+				}
+				_, err = buffer.WriteRune(r)
+				if err != nil {
+					return err
+				}
+				if strings.Contains(buffer.String(), str) {
+					return nil
+				}
+			}
+		}()
 	}()
-	for {
-		var r rune
-		r, _, err := p.runeReader.ReadRune()
-		require.NoError(p.t, err)
-		_, err = runeWriter.WriteRune(r)
-		require.NoError(p.t, err)
-		err = runeWriter.Flush()
-		require.NoError(p.t, err)
-		if strings.Contains(buffer.String(), str) {
-			break
+
+	select {
+	case err := <-match:
+		if err != nil {
+			p.t.Fatalf("%s: read error: %v (wanted %q; got %q)", time.Now(), err, str, buffer.String())
+			return ""
 		}
+		p.t.Logf("%s: matched %q = %q", time.Now(), str, buffer.String())
+		return buffer.String()
+	case <-timeout.Done():
+		// Ensure goroutine is cleaned up before test exit.
+		_ = p.out.closeErr(p.Close())
+		<-match
+
+		p.t.Fatalf("%s: match exceeded deadline: wanted %q; got %q", time.Now(), str, buffer.String())
+		return ""
 	}
-	p.t.Logf("matched %q = %q", str, stripAnsi.ReplaceAllString(buffer.String(), ""))
-	return buffer.String()
 }
 
 func (p *PTY) Write(r rune) {
+	p.t.Helper()
+
 	_, err := p.Input().Write([]byte{byte(r)})
 	require.NoError(p.t, err)
 }
 
 func (p *PTY) WriteLine(str string) {
+	p.t.Helper()
+
 	newline := []byte{'\r'}
 	if runtime.GOOS == "windows" {
 		newline = append(newline, '\n')
 	}
 	_, err := p.Input().Write(append([]byte(str), newline...))
 	require.NoError(p.t, err)
 }
+
+// stdbuf is like a buffered stdout, it buffers writes until read.
+type stdbuf struct {
+	r io.Reader
+
+	mu   sync.Mutex // Protects following.
+	b    []byte
+	more chan struct{}
+	err  error
+}
+
+func newStdbuf() *stdbuf {
+	return &stdbuf{more: make(chan struct{}, 1)}
+}
+
+func (b *stdbuf) Read(p []byte) (int, error) {
+	if b.r == nil {
+		return b.readOrWaitForMore(p)
+	}
+
+	n, err := b.r.Read(p)
+	if xerrors.Is(err, io.EOF) {
+		b.r = nil
+		err = nil
+		if n == 0 {
+			return b.readOrWaitForMore(p)
+		}
+	}
+	return n, err
+}
+
+func (b *stdbuf) readOrWaitForMore(p []byte) (int, error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	// Deplete channel so that more check
+	// is for future input into buffer.
+	select {
+	case <-b.more:
+	default:
+	}
+
+	if len(b.b) == 0 {
+		if b.err != nil {
+			return 0, b.err
+		}
+
+		b.mu.Unlock()
+		<-b.more
+		b.mu.Lock()
+	}
+
+	b.r = bytes.NewReader(b.b)
+	b.b = b.b[len(b.b):]
+
+	return b.r.Read(p)
+}
+
+func (b *stdbuf) Write(p []byte) (int, error) {
+	if len(p) == 0 {
+		return 0, nil
+	}
+
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if b.err != nil {
+		return 0, b.err
+	}
+
+	b.b = append(b.b, p...)
+
+	select {
+	case b.more <- struct{}{}:
+	default:
+	}
+
+	return len(p), nil
+}
+
+func (b *stdbuf) Close() error {
+	return b.closeErr(nil)
+}
+
+func (b *stdbuf) closeErr(err error) error {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	if b.err != nil {
+		return err
+	}
+	if err == nil {
+		b.err = io.EOF
+	} else {
+		b.err = err
+	}
+	close(b.more)
+	return err
+}
diff --git a/pty/ptytest/ptytest_internal_test.go b/pty/ptytest/ptytest_internal_test.go
@@ -0,0 +1,37 @@
+package ptytest
+
+import (
+	"bytes"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestStdbuf(t *testing.T) {
+	t.Parallel()
+
+	var got bytes.Buffer
+
+	b := newStdbuf()
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		_, err := io.Copy(&got, b)
+		assert.NoError(t, err)
+	}()
+
+	_, err := b.Write([]byte("hello "))
+	require.NoError(t, err)
+	_, err = b.Write([]byte("world\n"))
+	require.NoError(t, err)
+	_, err = b.Write([]byte("bye\n"))
+	require.NoError(t, err)
+
+	err = b.Close()
+	require.NoError(t, err)
+	<-done
+
+	assert.Equal(t, "hello world\nbye\n", got.String())
+}
diff --git a/pty/ptytest/ptytest_test.go b/pty/ptytest/ptytest_test.go
@@ -2,7 +2,6 @@ package ptytest_test
 
 import (
 	"fmt"
-	"runtime"
 	"strings"
 	"testing"
 
@@ -22,26 +21,24 @@ func TestPtytest(t *testing.T) {
 		pty.WriteLine("read")
 	})
 
+	// See https://github.com/coder/coder/issues/2122 for the motivation
+	// behind this test.
 	t.Run("Cobra ptytest should not hang when output is not consumed", func(t *testing.T) {
 		t.Parallel()
 
 		tests := []struct {
 			name          string
 			output        string
-			isPlatformBug bool // See https://github.com/coder/coder/issues/2122 for more info.
+			isPlatformBug bool
 		}{
 			{name: "1024 is safe (does not exceed macOS buffer)", output: strings.Repeat(".", 1024)},
-			{name: "1025 exceeds macOS buffer (must not hang)", output: strings.Repeat(".", 1025), isPlatformBug: true},
-			{name: "10241 large output", output: strings.Repeat(".", 10241), isPlatformBug: true}, // 1024 * 10 + 1
+			{name: "1025 exceeds macOS buffer (must not hang)", output: strings.Repeat(".", 1025)},
+			{name: "10241 large output", output: strings.Repeat(".", 10241)}, // 1024 * 10 + 1
 		}
 		for _, tt := range tests {
 			tt := tt
 			// nolint:paralleltest // Avoid parallel test to more easily identify the issue.
 			t.Run(tt.name, func(t *testing.T) {
-				if tt.isPlatformBug && (runtime.GOOS == "darwin" || runtime.GOOS == "windows") {
-					t.Skip("This test hangs on macOS and Windows, see https://github.com/coder/coder/issues/2122")
-				}
-
 				cmd := cobra.Command{
 					Use: "test",
 					RunE: func(cmd *cobra.Command, args []string) error {
