terminal_test.go

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package main_test
     6  
     7  import (
     8  	"errors"
     9  	"internal/testenv"
    10  	"internal/testpty"
    11  	"io"
    12  	"os"
    13  	"testing"
    14  
    15  	"golang.org/x/term"
    16  )
    17  
    18  func TestTerminalPassthrough(t *testing.T) {
    19  	// Check that if 'go test' is run with a terminal connected to stdin/stdout,
    20  	// then the go command passes that terminal down to the test binary
    21  	// invocation (rather than, e.g., putting a pipe in the way).
    22  	//
    23  	// See issue 18153.
    24  	testenv.MustHaveGoBuild(t)
    25  
    26  	// Start with a "self test" to make sure that if we *don't* pass in a
    27  	// terminal, the test can correctly detect that. (cmd/go doesn't guarantee
    28  	// that it won't add a terminal in the middle, but that would be pretty weird.)
    29  	t.Run("pipe", func(t *testing.T) {
    30  		r, w, err := os.Pipe()
    31  		if err != nil {
    32  			t.Fatalf("pipe failed: %s", err)
    33  		}
    34  		defer r.Close()
    35  		defer w.Close()
    36  		stdout, stderr := runTerminalPassthrough(t, r, w)
    37  		if stdout {
    38  			t.Errorf("stdout is unexpectedly a terminal")
    39  		}
    40  		if stderr {
    41  			t.Errorf("stderr is unexpectedly a terminal")
    42  		}
    43  	})
    44  
    45  	// Now test with a read PTY.
    46  	t.Run("pty", func(t *testing.T) {
    47  		r, processTTY, err := testpty.Open()
    48  		if errors.Is(err, testpty.ErrNotSupported) {
    49  			t.Skipf("%s", err)
    50  		} else if err != nil {
    51  			t.Fatalf("failed to open test PTY: %s", err)
    52  		}
    53  		defer r.Close()
    54  		w, err := os.OpenFile(processTTY, os.O_RDWR, 0)
    55  		if err != nil {
    56  			t.Fatal(err)
    57  		}
    58  		defer w.Close()
    59  		stdout, stderr := runTerminalPassthrough(t, r, w)
    60  		if !stdout {
    61  			t.Errorf("stdout is not a terminal")
    62  		}
    63  		if !stderr {
    64  			t.Errorf("stderr is not a terminal")
    65  		}
    66  	})
    67  }
    68  
    69  func runTerminalPassthrough(t *testing.T, r, w *os.File) (stdout, stderr bool) {
    70  	cmd := testenv.Command(t, testGo, "test", "-run=^$")
    71  	cmd.Env = append(cmd.Environ(), "GO_TEST_TERMINAL_PASSTHROUGH=1")
    72  	cmd.Stdout = w
    73  	cmd.Stderr = w
    74  
    75  	// The behavior of reading from a PTY after the child closes it is very
    76  	// strange: on Linux, Read returns EIO, and on at least some versions of
    77  	// macOS, unread output may be discarded (see https://go.dev/issue/57141).
    78  	//
    79  	// To avoid that situation, we keep the child process running until the
    80  	// parent has finished reading from the PTY, at which point we unblock the
    81  	// child by closing its stdin pipe.
    82  	stdin, err := cmd.StdinPipe()
    83  	if err != nil {
    84  		t.Fatal(err)
    85  	}
    86  
    87  	t.Logf("running %s", cmd)
    88  	err = cmd.Start()
    89  	if err != nil {
    90  		t.Fatalf("starting subprocess: %s", err)
    91  	}
    92  	w.Close()
    93  	t.Cleanup(func() {
    94  		stdin.Close()
    95  		if err := cmd.Wait(); err != nil {
    96  			t.Errorf("suprocess failed with: %s", err)
    97  		}
    98  	})
    99  
   100  	buf := make([]byte, 2)
   101  	n, err := io.ReadFull(r, buf)
   102  	if err != nil || !(buf[0] == '1' || buf[0] == 'X') || !(buf[1] == '2' || buf[1] == 'X') {
   103  		t.Logf("read error: %v", err)
   104  		t.Fatalf("expected 2 bytes matching `[1X][2X]`; got %q", buf[:n])
   105  	}
   106  	return buf[0] == '1', buf[1] == '2'
   107  }
   108  
   109  func init() {
   110  	if os.Getenv("GO_TEST_TERMINAL_PASSTHROUGH") == "" {
   111  		return
   112  	}
   113  
   114  	if term.IsTerminal(1) {
   115  		os.Stdout.WriteString("1")
   116  	} else {
   117  		os.Stdout.WriteString("X")
   118  	}
   119  	if term.IsTerminal(2) {
   120  		os.Stdout.WriteString("2")
   121  	} else {
   122  		os.Stdout.WriteString("X")
   123  	}
   124  
   125  	// Before exiting, wait for the parent process to read the PTY output,
   126  	// at which point it will close stdin.
   127  	io.Copy(io.Discard, os.Stdin)
   128  
   129  	os.Exit(0)
   130  }
   131
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