test(module): a blocked stdin write is released when the pump stops

commit: 487baa8b2c2efad3f01c9b7e0231e12c296204f1
author: brice · 13d ago · 2026-10-09 03:59 UTC
parent: 718054e
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

1 file · +42 -0

M internal/module/module_test.go +42 -0


@@ -227,6 +227,48 @@ func TestSendAllocs(t *testing.T) {
227	227		}
228	228		}
229	229
	230	+	// A script that never reads its stdin blocks the writer once the pipe is
	231	+	// full; stop must still return, because closing the pipe ends the Write.
	232	+	func TestPumpInputStopUnblocksAWrite(t *testing.T) {
	233	+	r, w, err := os.Pipe() // r is never read
	234	+	if err != nil {
	235	+	t.Fatal(err)
	236	+	}
	237	+	defer r.Close()
	238	+	m, _ := newTest()
	239	+	m.Interactive = true
	240	+	stop := m.pumpInput(w)
	241	+
	242	+	// Push well over the 64 KiB a pipe holds, until the queue stays full: then
	243	+	// the writer is stuck in Write.
	244	+	line := []byte(strings.Repeat("x", 100))
	245	+	sent := 0
	246	+	deadline := time.Now().Add(5 * time.Second)
	247	+	for full := 0; full < 50; {
	248	+	if time.Now().After(deadline) {
	249	+	t.Fatalf("the writer never blocked after %d lines", sent)
	250	+	}
	251	+	if m.Send(line) {
	252	+	sent++
	253	+	full = 0
	254	+	} else {
	255	+	full++
	256	+	time.Sleep(time.Millisecond)
	257	+	}
	258	+	}
	259	+	if sent*101 <= 64<<10 {
	260	+	t.Fatalf("only %d bytes went in; the pipe was not full", sent*101)
	261	+	}
	262	+
	263	+	done := make(chan struct{})
	264	+	go func() { stop(); close(done) }()
	265	+	select {
	266	+	case <-done:
	267	+	case <-time.After(time.Second):
	268	+	t.Fatal("stop did not return: the blocked Write was not released")
	269	+	}
	270	+	}
	271	+
230	272		func TestGenCountsStarts(t *testing.T) {
231	273		wake := make(chan struct{}, 1)
232	274		m := New("t", Left, "printf 'hi\\n'", wake, slog.New(slog.DiscardHandler))


@@ -227,6 +227,48 @@ func TestSendAllocs(t *testing.T) {
227	}	227		}
228	}	228		}
229		229
		230	+	// A script that never reads its stdin blocks the writer once the pipe is
		231	+	// full; stop must still return, because closing the pipe ends the Write.
		232	+	func TestPumpInputStopUnblocksAWrite(t *testing.T) {
		233	+	r, w, err := os.Pipe() // r is never read
		234	+	if err != nil {
		235	+	t.Fatal(err)
		236	+	}
		237	+	defer r.Close()
		238	+	m, _ := newTest()
		239	+	m.Interactive = true
		240	+	stop := m.pumpInput(w)
		241	+
		242	+	// Push well over the 64 KiB a pipe holds, until the queue stays full: then
		243	+	// the writer is stuck in Write.
		244	+	line := []byte(strings.Repeat("x", 100))
		245	+	sent := 0
		246	+	deadline := time.Now().Add(5 * time.Second)
		247	+	for full := 0; full < 50; {
		248	+	if time.Now().After(deadline) {
		249	+	t.Fatalf("the writer never blocked after %d lines", sent)
		250	+	}
		251	+	if m.Send(line) {
		252	+	sent++
		253	+	full = 0
		254	+	} else {
		255	+	full++
		256	+	time.Sleep(time.Millisecond)
		257	+	}
		258	+	}
		259	+	if sent*101 <= 64<<10 {
		260	+	t.Fatalf("only %d bytes went in; the pipe was not full", sent*101)
		261	+	}
		262	+
		263	+	done := make(chan struct{})
		264	+	go func() { stop(); close(done) }()
		265	+	select {
		266	+	case <-done:
		267	+	case <-time.After(time.Second):
		268	+	t.Fatal("stop did not return: the blocked Write was not released")
		269	+	}
		270	+	}
		271	+
230	func TestGenCountsStarts(t *testing.T) {	272		func TestGenCountsStarts(t *testing.T) {
231	wake := make(chan struct{}, 1)	273		wake := make(chan struct{}, 1)
232	m := New("t", Left, "printf 'hi\\n'", wake, slog.New(slog.DiscardHandler))	274		m := New("t", Left, "printf 'hi\\n'", wake, slog.New(slog.DiscardHandler))