Stop the terminal tests reading a pty nobody opened (closes #126)

On Linux, pty.Open of github.com/creack/pty v1.1.24 passes the address
of a local variable to ioctl as a plain number, through a function
call. When Go moved the goroutine's stack in between, the kernel wrote
the pty's number to the old place, and pty.Open opened /dev/pts/0,
another terminal. secret rm wrote there, and the test read a terminal
no program had open, which never ends. Require the commit on the
library's main branch that passes a pointer; no release has it yet.

Both terminal tests now stop reading when their one-minute context
ends, and fail saying what was still waiting.

Model: opus-5-5

internal/cli/integration_test.go

@@ -2601,7 +2601,9 @@ func TestRemoveWithoutTerminalFailsAtOnce(t *testing.T) {
 // and stderr, not both: whether it asks must depend on stdin alone, where
 // the answer is read from. pty.Open returns the two ends of a new terminal:
 // tty is the end a program uses as its terminal, and ptmx the end the test
-// reads what the terminal shows from and types into.
+// reads what the terminal shows from and types into. Reading ptmx stops at
+// the context's deadline, when secret rm is killed too, so a terminal that
+// stays open fails the test then instead of hanging it.
 
 // TestRemoveIgnoresTerminalOnStdout runs `echo y | secret rm x` at a
 // terminal. stdin is a pipe, so nobody can answer there, and the command
@@ -2619,6 +2621,9 @@ func TestRemoveIgnoresTerminalOnStdout(t *testing.T) {
 
 	defer func() { _ = ptmx.Close() }()
 
+	deadline, _ := ctx.Deadline()
+	require.NoError(t, ptmx.SetReadDeadline(deadline))
+
 	cmd.Stdin = strings.NewReader("y\n")
 	cmd.Stdout = tty
 	cmd.Stderr = tty
@@ -2628,9 +2633,15 @@ func TestRemoveIgnoresTerminalOnStdout(t *testing.T) {
 	_ = tty.Close()
 
 	// The read ends once secret rm has exited and so closed the terminal.
-	shown, _ := io.ReadAll(ptmx)
+	shown, err := io.ReadAll(ptmx)
+	require.NotErrorIs(t, err, os.ErrDeadlineExceeded,
+		"the terminal was still open a minute after secret rm started: %s",
+		shown)
 
-	require.Error(t, cmd.Wait())
+	err = cmd.Wait()
+
+	require.NoError(t, ctx.Err(), "secret rm did not exit within a minute")
+	require.Error(t, err)
 	assert.Contains(t, string(shown), "pass --force")
 	assert.DirExists(t, secretDir)
 }
@@ -2650,6 +2661,9 @@ func TestRemoveAsksAtTerminalOnStdin(t *testing.T) {
 
 	defer func() { _ = ptmx.Close() }()
 
+	deadline, _ := ctx.Deadline()
+	require.NoError(t, ptmx.SetReadDeadline(deadline))
+
 	cmd.Stdin = tty
 	// Not a file, so exec.Cmd connects stdout through a pipe.
 	cmd.Stdout = io.Discard
@@ -2667,7 +2681,8 @@ func TestRemoveAsksAtTerminalOnStdin(t *testing.T) {
 	terminal := bufio.NewReader(ptmx)
 	for !bytes.HasSuffix(shown, []byte("[y/N] ")) {
 		char, err = terminal.ReadByte()
-		require.NoError(t, err, "secret rm ended without asking: %s", shown)
+		require.NoError(t, err, "secret rm did not ask on the terminal: %s",
+			shown)
 
 		shown = append(shown, char)
 	}